Hi everyone I have made a power supply for my rigs

The schematic is the typical regulator with power transistor wrapped around
it for the extra juice.

I need 40 amps continues ..



I tried 4 mj2955 which are rather nice for foot warming in the winter .

I also tried nte-180 which are very good. is there anything better at a
logical price



I would like to keep the number of transistors down to 1 or 2.

Can someone advise my on what to use for power?

--
http://www.qsl.net/sv1hao

"Deos" wrote in message
...
Hi everyone I have made a power supply for my rigs

The schematic is the typical regulator with power transistor wrapped
around
it for the extra juice.

I need 40 amps continues ..
I tried 4 mj2955 which are rather nice for foot warming in the winter .

The function of the pass transistor is to dissipate as heat the difference
between input and output. Sounds like you need a bigger heat sink...or
build a switching supply.
Ray

Hi, check this link and see what you need to do,
one or two pass trans. will not do the job for you,
easier to use 6-10 pass trans to share the load.

http://www.mitedu.freeserve.co.uk/Ci...er/1230psu.htm

Is your transformer able to supply necessary power to this supply ?

regards,
clarke


Deos wrote:

Hi everyone I have made a power supply for my rigs

The schematic is the typical regulator with power transistor wrapped around
it for the extra juice.

I need 40 amps continues ..

I tried 4 mj2955 which are rather nice for foot warming in the winter .

I also tried nte-180 which are very good. is there anything better at a
logical price

I would like to keep the number of transistors down to 1 or 2.

Can someone advise my on what to use for power?

--
http://www.qsl.net/sv1hao

clarke wrote:
Hi, check this link and see what you need to do,
one or two pass trans. will not do the job for you,
easier to use 6-10 pass trans to share the load.

http://www.mitedu.freeserve.co.uk/Ci...er/1230psu.htm

Is your transformer able to supply necessary power to this supply ?

regards,
clarke


Deos wrote:


Hi everyone I have made a power supply for my rigs

The schematic is the typical regulator with power transistor wrapped around
it for the extra juice.

I need 40 amps continues ..

I tried 4 mj2955 which are rather nice for foot warming in the winter .

I also tried nte-180 which are very good. is there anything better at a
logical price

I would like to keep the number of transistors down to 1 or 2.

Can someone advise my on what to use for power?

--
http://www.qsl.net/sv1hao


If you want to keep it to a couple transistors they would be expensive.
You are better off using either more NTE-180 or more mj2955, but I would
cut the voltage down to around 18 volts instead of 24 volts as this
higher voltage leads to more heat for the transistors. Rob

On Mon, 20 Oct 2003 11:20:20 -0400, rob34 wrote:

If you want to keep it to a couple transistors they would be expensive.
You are better off using either more NTE-180 or more mj2955, but I would
cut the voltage down to around 18 volts instead of 24 volts as this
higher voltage leads to more heat for the transistors. Rob

How come no one's yet recommeded that great old PSU war-horse, the
2N3055? Six of them on a decent heat sink and you're sorted!

--

"Windows [n.], A thirty-two bit extension and GUI shell to a sixteen bit patch
to an eight bit operating system originally coded for a four bit
microprocessor and produced by a two bit company."

Paul Burridge wrote:
On Mon, 20 Oct 2003 11:20:20 -0400, rob34 wrote:


If you want to keep it to a couple transistors they would be expensive.
You are better off using either more NTE-180 or more mj2955, but I would
cut the voltage down to around 18 volts instead of 24 volts as this
higher voltage leads to more heat for the transistors. Rob


How come no one's yet recommeded that great old PSU war-horse, the
2N3055? Six of them on a decent heat sink and you're sorted!

2N3055 are great, but 2N3771 are better! Rob

rob34 wrote:

Paul Burridge wrote:
On Mon, 20 Oct 2003 11:20:20 -0400, rob34 wrote:


If you want to keep it to a couple transistors they would be expensive.
You are better off using either more NTE-180 or more mj2955, but I would
cut the voltage down to around 18 volts instead of 24 volts as this
higher voltage leads to more heat for the transistors. Rob


How come no one's yet recommeded that great old PSU war-horse, the
2N3055? Six of them on a decent heat sink and you're sorted!

2N3055 are great, but 2N3771 are better! Rob

True, but you can find 2N3055, or house numbered versions for free in
a lot of old linear power supplies pulled from junked equipment.
--


Michael A. Terrell
Central Florida

Hi, from Ken,
"rob34" wrote in message
...
Paul Burridge wrote:
On Mon, 20 Oct 2003 11:20:20 -0400, rob34 wrote:

2N3055 are great, but 2N3771 are better! Rob

2N3773 are better still ( check out current ).

If you want a power supply to deliver round about 40amps the the first thing
to remember is that you MUST have the correct amount of pass transistors to
handle the current.
If you use 2N3055's ( very good and cheap ) you will need at least 10 of
these, don't think for one minute becouse you see the current stated as
being 20amps that one transistor will be able to handle this amout of
current, it won't, it does not work like that.
The best you can hope for ( current wise ) from one 2N3055 is FIVE AMPS. So
for a forty amp supply you would need at least, eight and a couple for that
le-way we all try to allow.

One other thing you must have good heat sinks.

Regards the transformer, it should be able to handle the current and should
( ideally for a 13.8Volt supply ) be rated between 17.5 and 18.5 Volts of
load.
Once regulated this voltage will rise to about, 24 Volts + or - 1 or 2
Volts.

Regards regulation the most common way is to use the LM723 voltage regulator
chip complete with short circuit protection.

Smoothing caps should be another point of concern.
Try to find two large ripple handling units rated at about 40 Volts and
allow two thousand mfd
per one amp of current required.

One final point to remember when building your own power supply is to use
some form of ELECTRONIC OVER-VOLTAGE PROTECTION ( I.e., the MC3423 chip is
perfect ).
The number of cheap commercial power supplies on the market without
overvoltage protection fitted is a crime ( but they never tell you this in
the Ads..right..?. ).

Hope the above helps in some small way. Good luck, Ken, G4KIR.



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rob34 wrote:

Paul Burridge wrote:
On Mon, 20 Oct 2003 11:20:20 -0400, rob34 wrote:


If you want to keep it to a couple transistors they would be expensive.
You are better off using either more NTE-180 or more mj2955, but I would
cut the voltage down to around 18 volts instead of 24 volts as this
higher voltage leads to more heat for the transistors. Rob


How come no one's yet recommeded that great old PSU war-horse, the
2N3055? Six of them on a decent heat sink and you're sorted!

2N3055 are great, but 2N3771 are better! Rob

True, but you can find 2N3055, or house numbered versions for free in
a lot of old linear power supplies pulled from junked equipment.
--


Michael A. Terrell
Central Florida

Hi, from Ken,
"rob34" wrote in message
...
Paul Burridge wrote:
On Mon, 20 Oct 2003 11:20:20 -0400, rob34 wrote:

2N3055 are great, but 2N3771 are better! Rob

2N3773 are better still ( check out current ).

If you want a power supply to deliver round about 40amps the the first thing
to remember is that you MUST have the correct amount of pass transistors to
handle the current.
If you use 2N3055's ( very good and cheap ) you will need at least 10 of
these, don't think for one minute becouse you see the current stated as
being 20amps that one transistor will be able to handle this amout of
current, it won't, it does not work like that.
The best you can hope for ( current wise ) from one 2N3055 is FIVE AMPS. So
for a forty amp supply you would need at least, eight and a couple for that
le-way we all try to allow.

One other thing you must have good heat sinks.

Regards the transformer, it should be able to handle the current and should
( ideally for a 13.8Volt supply ) be rated between 17.5 and 18.5 Volts of
load.
Once regulated this voltage will rise to about, 24 Volts + or - 1 or 2
Volts.

Regards regulation the most common way is to use the LM723 voltage regulator
chip complete with short circuit protection.

Smoothing caps should be another point of concern.
Try to find two large ripple handling units rated at about 40 Volts and
allow two thousand mfd
per one amp of current required.

One final point to remember when building your own power supply is to use
some form of ELECTRONIC OVER-VOLTAGE PROTECTION ( I.e., the MC3423 chip is
perfect ).
The number of cheap commercial power supplies on the market without
overvoltage protection fitted is a crime ( but they never tell you this in
the Ads..right..?. ).

Hope the above helps in some small way. Good luck, Ken, G4KIR.



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
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