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6v & 90v DC Power supply
I need to generate 6v DC and 90v DC from a 12v DC automotive electrical
system to power an RT-70A/GRC surplus military radio. I need about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking about using the guts from an old battery back up but it would be a bit of a kluge. Are there any 90 volt regulators in the 78xx series? How do I get the voltage up to where I can get something that I can get the 90 volts from. Getting the 6 volts doesn't seem to be a problem. A 7806 off the battery should work for that unless any of you can see a problem doing that. Maybe the common common would be a problem. Right now I'm running it off of an HP6299A and an HP6236B with commons jumpered. I'd like to be able to go portable with it. |
6v & 90v DC Power supply
Hello James,
I need to generate 6v DC and 90v DC from a 12v DC automotive electrical system to power an RT-70A/GRC surplus military radio. I need about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking about using the guts from an old battery back up but it would be a bit of a kluge. Are there any 90 volt regulators in the 78xx series? How do I get the voltage up to where I can get something that I can get the 90 volts from. ... You can build a step-up or flyback with the LM3478. Tough to solder though, it's a TSSOP package. Don't know what current you need but just pick a suitable FET. For 6V I'd use a buck regulator instead of wasting 50% of the energy in a series regulator. Regards, Joerg http://www.analogconsultants.com |
6v & 90v DC Power supply
ORIGINAL MESSAGE: On Tue, 27 Dec 2005 02:02:15 GMT, "James F. Mayer" wrote: I need to generate 6v DC and 90v DC from a 12v DC automotive electrical system to power an RT-70A/GRC surplus military radio. I need about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking about using the guts from an old battery back up but it would be a bit of a kluge. Are there any 90 volt regulators in the 78xx series? How do I get the voltage up to where I can get something that I can get the 90 volts from. Getting the 6 volts doesn't seem to be a problem. A 7806 off the battery should work for that unless any of you can see a problem doing that. Maybe the common common would be a problem. Right now I'm running it off of an HP6299A and an HP6236B with commons jumpered. I'd like to be able to go portable with it. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I'd use one of those small inexpensive inverters which put out 120vac and then use a conventional transformer/rectifier system. You can pick up the inverter at any truck stop. 73, Bill W6WRT |
6v & 90v DC Power supply
I'd use one of those small inexpensive inverters which put out 120vac
and then use a conventional transformer/rectifier system. You can pick up the inverter at any truck stop. ============================ Those 'inexpensive inverters' might need some attention in respect of the 'hash' they create , possibly causing interference in the receiver. Frank |
6v & 90v DC Power supply
I need to generate 6v DC and 90v DC from a 12v DC automotive electrical system [to power an RT-70A/GRC surplus military radio]. I need about 250 mA at +6 volts and about 75 mA at +90 volts. [ I was thinking about using the guts from an old battery back up but it would be a bit of a kluge.] Are there any 90 volt regulators in the 78xx series? How do I get the voltage up to where I can get something that I can get the 90 volts from. Getting the 6 volts doesn't seem to be a problem. A 7806 off the battery should work for that unless any of you can see a problem doing that. [ Maybe the common common would be a problem. Right now I'm running it off of an HP6299A and an HP6236B with commons jumpered. I'd like to be able to go portable with it. ] 90V @70ma is only 6.3W and a step-up of no more than 90/12=7.5. This would be something like a 24VAC center-tapped transformer turned backwards with a multivibrator drive of the secondary at 50-60Hz and the usual primary is rectified and capacitor filtered to produce the 90V. Since the reflected current is only about 1/2A, you can then feedback the rectified HV to drive an error amp that regulates the center tap down to 9V or so. |
6v & 90v DC Power supply
On Tue, 27 Dec 2005 02:02:15 GMT, "James F. Mayer"
wrote: I need to generate 6v DC and 90v DC from a 12v DC automotive electrical system to power an RT-70A/GRC surplus military radio. I need about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking about using the guts from an old battery back up but it would be a bit of a kluge. Are there any 90 volt regulators in the 78xx series? How do I get the voltage up to where I can get something that I can get the 90 volts from. Getting the 6 volts doesn't seem to be a problem. A 7806 off the battery should work for that unless any of you can see a problem doing that. Maybe the common common would be a problem. Right now I'm running it off of an HP6299A and an HP6236B with commons jumpered. I'd like to be able to go portable with it. Hello James, Speaking as a cheapskate ham/hobbyist, how about salvaging parts from a computer power supply. Find a dud power supply for free at computer shops/dumpsters/rubbish tips/roadside etc. Salvage the TL494 integrated circuit that can be found in many computer power supplies. You could build a 90 Volt power supply as Ray Robinson has down here http://www.shlrc.mq.edu.au/~robinson...verter_4W.html Here is a link to the TL494 Data sheet http://focus.ti.com/lit/ds/symlink/tl494.pdf This link tells you how to use the TL494 IC http://focus.ti.com/lit/an/slva001d/slva001d.pdf Use another TL494 in a buck converter for your 12 Volts to 6Volts power supply module. Look at the bottom of this page for more info. http://focus.ti.com/docs/prod/folders/print/tl494.html Your 7806 is probably a better idea, saves a lot of messing about. Or you could use the guts of a mobile phone car charger. The charger that fits into the cigarette lighter in a motor car. You can find them in pawn shops for a dollar or two. Dud ones even cheaper. Usually just a broken connection from rough handling. http://www.onsemi.com/pub/Collateral/MC34063A-D.PDF Look at page 7 Figure 10 Step down converter. In the few car phone chargers that I opened, the IC was a MC34063 and the schematic was very similar to that shown in figure 10 Just change R1 or R2 slightly so that you get 6 Volts out. You may have to check/change the value of resistor Rsc to be closer to that shown in figure 10 You might even get away with not changing the inductor. Try it and see if the original inductor works well enough for you. A ton of reading, bits and pieces for free or dirt cheap. What a great hobby, this is James, eh! Regards, John Crighton Sydney |
6v & 90v DC Power supply
On Tue, 27 Dec 2005 02:02:15 GMT, "James F. Mayer"
wrote: I need to generate 6v DC and 90v DC from a 12v DC automotive electrical system to power an RT-70A/GRC surplus military radio. I need about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking about using the guts from an old battery back up but it would be a bit of a kluge. Are there any 90 volt regulators in the 78xx series? How do I get the voltage up to where I can get something that I can get the 90 volts from. Getting the 6 volts doesn't seem to be a problem. A 7806 off the battery should work for that unless any of you can see a problem doing that. Maybe the common common would be a problem. Right now I'm running it off of an HP6299A and an HP6236B with commons jumpered. I'd like to be able to go portable with it. Hello again James, I just came across this site while looking for something else. http://web.telia.com/~u85920178/use/tubepsu.htm Look at the the 6V AC from 12 V DC. Nifty! Here is another http://www.i4at.org/lib2/inverter.htm You want DC out so you will have to fit a bridge rectifier and filter capacitors to the output of the transformer just like Harry Lythall's circuit above. Regards, John Crighton Sydney |
6v & 90v DC Power supply
ORIGINAL MESSAGE: On Mon, 26 Dec 2005 21:11:35 -0800, Highland Ham wrote: Those 'inexpensive inverters' might need some attention in respect of the 'hash' they create , possibly causing interference in the receiver. Frank ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ True for any kind of inverter. 73, Bill W6WRT |
6v & 90v DC Power supply
ORIGINAL MESSAGE: On Tue, 27 Dec 2005 05:58:18 GMT, (John Crighton) wrote: Hello James, Speaking as a cheapskate ham/hobbyist, how about salvaging parts from a computer power supply. Find a dud power supply for free at computer shops/dumpsters/rubbish tips/roadside etc. Salvage the TL494 integrated circuit that can be found in many computer power supplies. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Excellent info, John. Thanks!! 73, Bill W6WRT |
6v & 90v DC Power supply
On Tue, 27 Dec 2005 02:02:15 GMT, "James F. Mayer"
wrote: I need to generate 6v DC and 90v DC from a 12v DC automotive electrical system to power an RT-70A/GRC surplus military radio. I need about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking about using the guts from an old battery back up but it would be a bit of a kluge. Are there any 90 volt regulators in the 78xx series? How do I get the voltage up to where I can get something that I can get the 90 volts from. Getting the 6 volts doesn't seem to be a problem. A 7806 off the battery should work for that unless any of you can see a problem doing that. Maybe the common common would be a problem. Right now I'm running it off of an HP6299A and an HP6236B with commons jumpered. I'd like to be able to go portable with it. Google "GLOWBUGS" as there are a number of small tube based sites that have dealt with this problem. Allison Spam/adverts severly not wanted. |
6v & 90v DC Power supply
Do it the way the original radio did it -- dynamotor. You can still find
them in the back room at a lot of military surplus electronics junk stores. Jim |
6v & 90v DC Power supply
Hello Jim,
Do it the way the original radio did it -- dynamotor. You can still find them in the back room at a lot of military surplus electronics junk stores. But then be prepared for some major restoration. The bearings of a lot of these are nearly shot, mostly from sitting in an attic for decades. It's like old pond pumps. They run fine for a few weeks and then the racket increases, some weird noises appear, things get hot and they seize up. I restored an old Hammond organ. These generate the tones in a similar manner. A motor (plus a start motor) and over a hundred pickup coils on the long secondary shaft. 20 hours of hard work got it going again but we have accepted the fact that some of the bearings are pretty much over the hill. So it needs 2-3 starts to coax it to run without that mild screeching in the background. Getting spare parts from a company that went out of business 30 years ago just isn't going to happen. Regards, Joerg http://www.analogconsultants.com |
6v & 90v DC Power supply
|
6v & 90v DC Power supply
On Tue, 27 Dec 2005 18:59:56 +0000, Joerg wrote:
Hello Jim, Do it the way the original radio did it -- dynamotor. You can still find them in the back room at a lot of military surplus electronics junk stores. But then be prepared for some major restoration. The bearings of a lot of these are nearly shot, mostly from sitting in an attic for decades. It's like old pond pumps. They run fine for a few weeks and then the racket increases, some weird noises appear, things get hot and they seize up. I restored an old Hammond organ. These generate the tones in a similar manner. A motor (plus a start motor) and over a hundred pickup coils on the long secondary shaft. 20 hours of hard work got it going again but we have accepted the fact that some of the bearings are pretty much over the hill. So it needs 2-3 starts to coax it to run without that mild screeching in the background. Getting spare parts from a company that went out of business 30 years ago just isn't going to happen. So, put the cam thingie on some sort of spindle, with some kind of depth gauge thingie, (maybe a slide pot and a stick), and map the disks, and just make the same waveform from ROM? Good Luck! Rich |
6v & 90v DC Power supply
Hello Rich,
I restored an old Hammond organ. These generate the tones in a similar manner. A motor (plus a start motor) and over a hundred pickup coils on the long secondary shaft. 20 hours of hard work got it going again but we have accepted the fact that some of the bearings are pretty much over the hill. So it needs 2-3 starts to coax it to run without that mild screeching in the background. Getting spare parts from a company that went out of business 30 years ago just isn't going to happen. So, put the cam thingie on some sort of spindle, with some kind of depth gauge thingie, (maybe a slide pot and a stick), and map the disks, and just make the same waveform from ROM? That has been tried many times. Several rather expensive electronic organs have come out claiming to emulate a Hammond. So far the real enthusiasts do anything to get their hands on the real thing, knowing that there will come a day when the last one croaks. IIRC it was Paul Shaffer (the guy who makes the music at david Letterman's show) who spent the equivalent of a luxury car to have one restored. Regards, Joerg http://www.analogconsultants.com |
6v & 90v DC Power supply
"David Harmon" wrote in message ... On Tue, 27 Dec 2005 05:58:18 GMT in sci.electronics.design, (John Crighton) wrote, This link tells you how to use the TL494 IC http://focus.ti.com/lit/an/slva001d/slva001d.pdf So why is the guy from TI showing NTE transistors for the power switching? Nothing in the TIP line good enough? Probably good enough for his measly 32 volts. I need to modify that circuit to work on outputs of 90 volts and 6 volts. |
6v & 90v DC Power supply
On Tue, 27 Dec 2005 21:27:31 +0000, Joerg wrote:
Hello Rich, I restored an old Hammond organ. These generate the tones in a similar manner. A motor (plus a start motor) and over a hundred pickup coils on the long secondary shaft. 20 hours of hard work got it going again but we have accepted the fact that some of the bearings are pretty much over the hill. So it needs 2-3 starts to coax it to run without that mild screeching in the background. Getting spare parts from a company that went out of business 30 years ago just isn't going to happen. So, put the cam thingie on some sort of spindle, with some kind of depth gauge thingie, (maybe a slide pot and a stick), and map the disks, and just make the same waveform from ROM? That has been tried many times. Several rather expensive electronic organs have come out claiming to emulate a Hammond. So far the real enthusiasts do anything to get their hands on the real thing, knowing that there will come a day when the last one croaks. IIRC it was Paul Shaffer (the guy who makes the music at david Letterman's show) who spent the equivalent of a luxury car to have one restored. Well, tastes vary, but really! Who wants a music box that makes it sound like you're at a skating rink? ;-P cheers! Rich |
6v & 90v DC Power supply
Hello Rich,
Well, tastes vary, but really! Who wants a music box that makes it sound like you're at a skating rink? ;-P Ok, I am not much of an expert on instruments or music in general. But a Hammond organ can fill a living room with a sound that, with the eyes closed, you'd think you are sitting in a cathedral. And lots of rock bands wouldn't use anything else. That is why a lot of Hammonds have been "sawed in halves" so they can be transported to the next gig. You could even buy split versions built into professional transport cases. Regards, Joerg http://www.analogconsultants.com |
6v & 90v DC Power supply
Joerg wrote:
Hello Rich, Well, tastes vary, but really! Who wants a music box that makes it sound like you're at a skating rink? ;-P Ok, I am not much of an expert on instruments or music in general. But a Hammond organ can fill a living room with a sound that, with the eyes closed, you'd think you are sitting in a cathedral. And lots of rock bands wouldn't use anything else. That is why a lot of Hammonds have been "sawed in halves" so they can be transported to the next gig. You could even buy split versions built into professional transport cases. Regards, Joerg http://www.analogconsultants.com They have a Hammond B3 at my church, with the Leslie speaker. There is another model Hammond in storage that needs a lot of work. Someone had it on their screened in porch and the finish is ruined, but it still plays. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
6v & 90v DC Power supply
"Rich Grise, but drunk" wrote:
Well, tastes vary, but really! Who wants a music box that makes it sound like you're at a skating rink? ;-P cheers! Rich People like the old Hammond organs like the B3 because the can't go out of tune. The mechanical tone generator makes sure of that. They only sound like a skating rink in, get this, A SKATING RINK! -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
6v & 90v DC Power supply
Hello Michael,
They have a Hammond B3 at my church, with the Leslie speaker. There is another model Hammond in storage that needs a lot of work. Someone had it on their screened in porch and the finish is ruined, but it still plays. Just make sure that the oiling intervals are religiously kept. If the other one still plays be grateful for that. If it's the same model or nearly the same keep it. Even if the finish is beyond repair some day you might be really thankful to be able to scavenge its tone generator once the TG on the other Hammond goes. A bad finish is often easy to fix compared to taking the whole machinery apart. Ours has a superb finish condition but it had been run dry for more than a decade before it was given to us. So the TG is quite worn :-( Actually it was so bad that when I was done it gulped almost two cans of Hammond oil. Some words of caution: The rectifier tube of the amp in the bottom is located pretty close to the back and it gets freaking hot. I would take care that the organ is never placed against a curtain or other flammable material and that nobody stores any stuff behind it. The power cord on ours almost crumbled in my hands and when attemting to swap it I discovered that this instrument did not have a single fuse. So I made a nice box with fuse and IEC connector. Regards, Joerg http://www.analogconsultants.com |
6v & 90v DC Power supply
On Wed, 28 Dec 2005 01:34:30 +0000, Michael A. Terrell wrote:
"Rich Grise, but drunk" wrote: Well, tastes vary, but really! Who wants a music box that makes it sound like you're at a skating rink? ;-P People like the old Hammond organs like the B3 because the can't go out of tune. The mechanical tone generator makes sure of that. They only sound like a skating rink in, get this, A SKATING RINK! Well, being the insufferabley pedantic researcher that I am, I came up with a page: http://en.wikipedia.org/wiki/Hammond_organ that about a third of the way down, says: "... Accurate imitation of the Hammond sound with simple electronic circuitry was difficult, because the subtly-changing phase relationships between tonewheels could not be easily replicated...." OK, fair enough. :-) I guess a piano is even harder - they don't even reproduce well from a live recording! :-) Cheers! Rich |
6v & 90v DC Power supply
Hello Rich,
that about a third of the way down, says: "... Accurate imitation of the Hammond sound with simple electronic circuitry was difficult, because the subtly-changing phase relationships between tonewheels could not be easily replicated...." OK, fair enough. :-) Even with complicated electronics it wasn't. IIRC it was Suzuki-Hammond which came out with the XK2 and then the XK3. Those are pretty elaborate synthesizer organs. But according to the experts it just ain't the same. Regards, Joerg http://www.analogconsultants.com |
6v & 90v DC Power supply
Buy a DC-DC converter that includes other protection
features (ie overvoltage and overcurrent protection) and outputs known parameters (ie ripple voltage). I doubt you will find a single DC-DC converter for both voltages. But a small converter for each voltage should work. Many sources including this one that just arrived on my desk - www.astrodyne.com . BTW, power from automotive systems should also worry about load dump. Technically load dump can be a transient as much as 270 volts on a 12 volt system. In reality, such events may only be 50 volts or less. Transients that would not damage other automotive electronics already designed for this rare and so destructive event. That is a problem with some regulators such as 78xx series. Maximum voltage is typically not sufficient for automotive purposes - would require additional protection. "James F. Mayer" wrote: Probably good enough for his measly 32 volts. I need to modify that circuit to work on outputs of 90 volts and 6 volts. |
6v & 90v DC Power supply
On Wed, 28 Dec 2005 02:42:58 +0000, Joerg wrote:
Hello Rich, that about a third of the way down, says: "... Accurate imitation of the Hammond sound with simple electronic circuitry was difficult, because the subtly-changing phase relationships between tonewheels could not be easily replicated...." OK, fair enough. :-) Even with complicated electronics it wasn't. IIRC it was Suzuki-Hammond which came out with the XK2 and then the XK3. Those are pretty elaborate synthesizer organs. But according to the experts it just ain't the same. It seems like, no matter how closely you try to mimic the waveform of a real instrument, there's always something that says, "This is electronic." Or, maybe more accurately, "This is not real." ;-) Cheers! Rich |
6v & 90v DC Power supply
On Wed, 28 Dec 2005 02:20:02 -0500, w_tom wrote:
On Wed, 28 Dec 2005 02:20:02 -0500, w_tom top-posted: .... BTW, power from automotive systems should also worry about load dump. Technically load dump can be a transient as much as 270 volts on a 12 volt system. In reality, such events may only be 50 volts or less. Transients that would not damage other automotive electronics already designed for this rare and so destructive event. That is a problem with some regulators such as 78xx series. Maximum voltage is typically not sufficient for automotive purposes - would require additional protection. This is what transzorbs http://www.vishay.com/docs/88301/15ke.pdf and hash chokes are for. I'm not affiliated with Vishay, formerly General Semiconductor, just a satisfied customer. I've used them to protect circuits against the transients caused by a 5 KV arc in an ion gun. :-) Cheers! Rich "James F. Mayer" wrote: Probably good enough for his measly 32 volts. I need to modify that circuit to work on outputs of 90 volts and 6 volts. |
6v & 90v DC Power supply
"John Crighton" wrote in message ... On Tue, 27 Dec 2005 02:02:15 GMT, "James F. Mayer" wrote: I need to generate 6v DC and 90v DC from a 12v DC automotive electrical system to power an RT-70A/GRC surplus military radio. I need about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking about using the guts from an old battery back up but it would be a bit of a kluge. Are there any 90 volt regulators in the 78xx series? How do I get the voltage up to where I can get something that I can get the 90 volts from. Getting the 6 volts doesn't seem to be a problem. A 7806 off the battery should work for that unless any of you can see a problem doing that. Maybe the common common would be a problem. Right now I'm running it off of an HP6299A and an HP6236B with commons jumpered. I'd like to be able to go portable with it. Hello again James, I just came across this site while looking for something else. http://web.telia.com/~u85920178/use/tubepsu.htm Look at the the 6V AC from 12 V DC. Nifty! Here is another http://www.i4at.org/lib2/inverter.htm You want DC out so you will have to fit a bridge rectifier and filter capacitors to the output of the transformer just like Harry Lythall's circuit above. Regards, John Crighton Sydney I'm going to build a modified Lythall but I need to determine what the wattage of the 330 Ohm resisters would be. I'm thinking they should be fairly high. |
6v & 90v DC Power supply
Actually SGS Thompson that specifically makes protectors for
automobiles and load dump (do what 'too small' transzorb would also do) acknowledge in their app notes that: " ... there are several existing products products able to clamp this overvoltage at the board level, for example the LDP24 or RBO series. The protection at the alternator level is a quite new concept and all the technical problems do not seem to be completely solved." This would explain why an 'up to 270 volt' transient is not routinely observed. Still, automotive electronics typically should withstand about 50 volts ballpark without damage. Transzorb could be but one part of that protection system. Or a DC to DC converter that specifically has such protection could be obtained. A weakness of Transzorbs are their low power abilities. The advantage - those avalanche diodes can handle so much more power than conventional zeners. My first design that used Transzorb was maybe 20 years ago. GS was selling Transzorbs even long before then. Load dump does not occur frequently. But that one time can be so destructive. Best to consider load dump when attaching any electronics to automotive power because even trivial protection does so much. Rich Grise wrote: This is what transzorbs http://www.vishay.com/docs/88301/15ke.pdf and hash chokes are for. I'm not affiliated with Vishay, formerly General Semiconductor, just a satisfied customer. I've used them to protect circuits against the transients caused by a 5 KV arc in an ion gun. :-) |
6v & 90v DC Power supply
"James F. Mayer" wrote in message
nk.net... I need to generate 6v DC and 90v DC from a 12v DC automotive electrical system to power an RT-70A/GRC surplus military radio. I need about 250 mA at +6 volts and about 75 mA at +90 volts. I was thinking about using the guts from an old battery back up but it would be a bit of a kluge. Are there any 90 volt regulators in the 78xx series? How do I get the voltage up to where I can get something that I can get the 90 volts from. Getting the 6 volts doesn't seem to be a problem. A 7806 off the battery should work for that unless any of you can see a problem doing that. Maybe the common common would be a problem. Right now I'm running it off of an HP6299A and an HP6236B with commons jumpered. I'd like to be able to go portable with it. You will find a number of solutions (e.g. battery radios) in the Usenet group: rec.antiques.radio_phono gb |
6v & 90v DC Power supply
Hello Rich,
It seems like, no matter how closely you try to mimic the waveform of a real instrument,... I have a feeling that this is exactly the problem. Engineers try to mimic the output waveform instead of looking how the real instrument is built. If they did that, they'd try to emulate all the individual parts and pieces. Regards, Joerg http://www.analogconsultants.com |
6v & 90v DC Power supply
Rich Grise, but drunk wrote:
"... Accurate imitation of the Hammond sound with simple electronic circuitry was difficult, because the subtly-changing phase relationships between tonewheels could not be easily replicated...." OK, fair enough. :-) I guess a piano is even harder - they don't even reproduce well from a live recording! :-) I heard a decently accurate electronic piano sound long before I heard anything remotely resembling the timber of a B3. Still haven't heard anything that sounds exactly like a B3 (other than an A100 or another B3). -- If John McCain gets the 2008 Republican Presidential nomination, my vote for President will be a write-in for Jiang Zemin. |
6v & 90v DC Power supply
On Wed, 28 Dec 2005 22:03:48 +0000, Joerg wrote:
Hello Rich, It seems like, no matter how closely you try to mimic the waveform of a real instrument,... I have a feeling that this is exactly the problem. Engineers try to mimic the output waveform instead of looking how the real instrument is built. If they did that, they'd try to emulate all the individual parts and pieces. Regards, Joerg http://www.analogconsultants.com Yabbut, how many gyrators and phase shifters and stuff does it take to model, for example, a bowed string? ;-) Thanks! Rich |
6v & 90v DC Power supply
On Thu, 29 Dec 2005 01:06:02 GMT, the renowned Rich Grise
wrote: On Wed, 28 Dec 2005 22:03:48 +0000, Joerg wrote: Hello Rich, It seems like, no matter how closely you try to mimic the waveform of a real instrument,... I have a feeling that this is exactly the problem. Engineers try to mimic the output waveform instead of looking how the real instrument is built. If they did that, they'd try to emulate all the individual parts and pieces. Regards, Joerg http://www.analogconsultants.com Yabbut, how many gyrators and phase shifters and stuff does it take to model, for example, a bowed string? ;-) Thanks! Rich Whatever it is, if it has to come out of speakers it isn't going to sound quite right. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
6v & 90v DC Power supply
Hello Spehro,
Whatever it is, if it has to come out of speakers it isn't going to sound quite right. In case of a Hammond organ it might since it has a speaker. Of course, it's a tube amp but that is a whole other matter which alone could make this thread balloon. It'll take a lot of gyrators and filters but considering that one can buy a 400MHz DSP for less than a crate of beer these days it should be feasible. In case of our piano the DSP still couldn't win. The piano doesn't need power. Not even light since it has its own candles. Regards, Joerg http://www.analogconsultants.com |
6v & 90v DC Power supply
On Tue, 27 Dec 2005 18:59:56 GMT, Joerg
wrote: Hello Jim, Do it the way the original radio did it -- dynamotor. You can still find them in the back room at a lot of military surplus electronics junk stores. But then be prepared for some major restoration. The bearings of a lot of these are nearly shot, mostly from sitting in an attic for decades. It's like old pond pumps. They run fine for a few weeks and then the racket increases, some weird noises appear, things get hot and they seize up. I restored an old Hammond organ. These generate the tones in a similar manner. A motor (plus a start motor) and over a hundred pickup coils on the long secondary shaft. 20 hours of hard work got it going again but we have accepted the fact that some of the bearings are pretty much over the hill. So it needs 2-3 starts to coax it to run without that mild screeching in the background. Getting spare parts from a company that went out of business 30 years ago just isn't going to happen. Regards, Joerg http://www.analogconsultants.com what kind of bearings? - ball bearings are like tubes - thay have numbers and substitutes. Bronze bearings are routinely made by machinists. Babbit is hardest as it is poured in place but you might be better off replacing them with something else like bronze. Bearing technology is not all that complicated if you poke into the right group of folks. |
6v & 90v DC Power supply
On Thu, 29 Dec 2005 02:13:05 GMT, the renowned Joerg
wrote: Hello Spehro, Whatever it is, if it has to come out of speakers it isn't going to sound quite right. In case of a Hammond organ it might since it has a speaker. Of course, it's a tube amp but that is a whole other matter which alone could make this thread balloon. Don't some of them have rotating speakers? It'll take a lot of gyrators and filters but considering that one can buy a 400MHz DSP for less than a crate of beer these days it should be feasible. In case of our piano the DSP still couldn't win. The piano doesn't need power. Not even light since it has its own candles. Regards, Joerg http://www.analogconsultants.com Sure, but can you flip a switch and be playing the flute or er-hu? Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
6v & 90v DC Power supply
Spehro Pefhany wrote:
Don't some of them have rotating speakers? That is a "Leslie" speaker. I have to service the one at my church. The bearings are shot. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
6v & 90v DC Power supply
"Rich Grise" bravely wrote to "All" (29 Dec 05 01:06:02)
--- on the heady topic of " 6v & 90v DC Power supply" RG From: Rich Grise RG Xref: core-easynews rec.radio.amateur.homebrew:90355 RG sci.electronics.design:535244 RG On Wed, 28 Dec 2005 22:03:48 +0000, Joerg wrote: Hello Rich, It seems like, no matter how closely you try to mimic the waveform of a real instrument,... I have a feeling that this is exactly the problem. Engineers try to mimic the output waveform instead of looking how the real instrument is built. If they did that, they'd try to emulate all the individual parts and pieces. Regards, Joerg http://www.analogconsultants.com RG Yabbut, how many gyrators and and stuff does it take to RG model, for example, a bowed string? ;-) RG Thanks! RG Rich One wouldn't use gyrators and phase shifters but rather wavetables. In a nutshell, it is a sample (digital recording) of the real instrument. Then it is digitally manipulated to add modulation, timbre characteristics, and whatever other effects are required for the instrument. This is calculated for each note and stored in a table in memory, hence the name wavetable. Then this is read out to the digital to analog converter. The resulting sound is hard to tell apart from the real instrument. Another even more realistic and versatile method uses digital building blocks to mimic each physical component. For example in the case of the human voice, the nose, the mouth, windpipe, etc. One can create totally non-existant instruments like a violin that sounds like a flute or whatever else you could possibly imagine. There is a program which does this but I'm drawing a blank now. A*s*i*m*o*v .... Guitar smashing doesn't bother me. Some "need" smashing. -Chet Atkins |
6v & 90v DC Power supply
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6v & 90v DC Power supply
I bet you can get replacement
bearings from searching on the web http://www.mitatechs.com/organcom.html http://www.tonewheelgeneral.com/ http://www.goffprof.com/ |
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