I have also seen thermistors used as a self regulating thermal element
for a crystal oven.

Joe Leikhim K4SAT
"The RFI-EMI-GUY"

"Follow The Money"



Pooh Bear wrote:

John Larkin wrote:



TO-220 bipolar transistors make nice temperature sensors.



I like that trick. Esp the isolated tab type.

Graham




--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"

"Follow The Money"

John Larkin wrote:

A 1N4007 can also be used as a drift step-recovery diode and as a
plasma avalanche diode. Together, two can generate a kilovolt edge
with a 100 ps risetime.

GAASfets make good fast analog switches; they behave pretty much like
jfets.

Wide-open LDO regulators make nice resettable fuses.

Ferrite beads do all sorts of interesting stuff.

Power mosfets make good heaters, and TO-220 bipolar transistors make
nice temperature sensors.

LVDS line receivers are surprisingly good comparators, and *fast*


I could go on...

John

tell us more John

NT

On Thu, 24 Nov 2005 09:40:27 +0100, "Henry Kiefer"
wrote:

Hi all -

After my first thread going from "standard" cheap parts for up to vhf
frequency to a discussion about the usefulness of Spice simulator...... I
try it another time hopefully get attention of frustrated co-readers:

For example the rechtifier diode 1N4007 can be used as a rf switching diode,
for example as rx/tx-switch. This is because it is a pin structure diode.
[snip]

Best regards -
Henry


That's an interesting use of the 1N4007. I've not tried that, what
kind of off capacitance do you get?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Cadmium sulphide ( CdS ) LDR as a Beta radiation detector. Not sensitive to
Gamma radiation which can be an advantage because it will detect Beta in
presence of Gamma. You have to paint it black. Horrible temperature
sensitivity but you can use another CdS as reference.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

On Thu, 24 Nov 2005 09:40:27 +0100, "Henry Kiefer"
wrote:

Hi all -

After my first thread going from "standard" cheap parts for up to vhf
frequency to a discussion about the usefulness of Spice simulator...... I
try it another time hopefully get attention of frustrated co-readers:

For example the rechtifier diode 1N4007 can be used as a rf switching diode,
for example as rx/tx-switch. This is because it is a pin structure diode.
This type is cheap and you can get it almost everywhere. It shows good
performance for the price. Surely for high-end you should do it with another
type tuned to the application it is made for. But anyway it works in some
circuits.

Do you know of other interesting devices or circuits good for misuse?

Best regards -
Henry

1n4007 as varactor (freq multiplier) and also Varicap.
You already mentioned RX/TX swich.
Also in PIN attenuator circuits.

Glass cased rectifiers (1n4007 in glass rather than epoxy)
as photodiode.

1n914 as 2ghz multipler (as varactor) to 100mw output.

1n914/4148 as silicon temperature sensor. (forward bias)

Base emitter of NPN silicon transistors as Zeners (5-8Vrange).
Makes a decent noise diode that way too.

Base collector of NPN si transistor as Varicap

Collector emitter of silicon transistors reverse biased as negative
resistance device.

Open GE and SI transistors are sensitive photodetectors.

Opened SCRs as photoswitches.


Allison

) writes:

1n4007 as varactor (freq multiplier) and also Varicap.
That's not really a new thing, or specific to the 1N4007.

Sam Harris, in that first article about parametric amplifiers in
CQ circa 1958, goes into detail of what's required, and then
practically leaves the issue of the varactor to the end. At
the time, they were new, likely expensive, and not easy to get.
Sam had it easy, he worked at Microwave Associates at the time.
So then towards the end of the article where he attends to the
issue of the varactor, he basically says use whatever's available,
try things, and at least practice with those other devices until
you get good at it, at which point it's time for the "real thing".
I have quoted that bit in the past, but I don't know where I've
put the article to get the exact wording.

And ever since then, influenced by his words or maybe independent
thought, the magazines have been full of mention of using whatever's
available as a varactor, the results varying with the diode (or
junction, since some have used part of a transistor) and of course
the application.

And of course, there was one article where the author mentioned a lot
of hum in his six meter synthesizer that used something like a 1N914
for the varactor. He then realizes that the problem was the light
of a nearby lamp getting to the actual diode theough the glass
case of the diode, and hence modulating the VCO that way.

Michael VE2BVW

wrote:
1n914/4148 as silicon temperature sensor. (forward bias)
I used a 1n4007 as a temperature sensor to repair a water bed
heater.

1n914/4148 as silicon temperature sensor. (forward bias)

I used a 1n4007 as a temperature sensor to repair a water bed
heater.

What is the rest of the circuit you used?

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

wrote:
1n914/4148 as silicon temperature sensor. (forward bias)


I used a 1n4007 as a temperature sensor to repair a water bed
heater.

What is the rest of the circuit you used?

A 741 op amp was used as a comparator driving an opto-isolator
triac driver. A triac then controlled the heater. The op amp
compared the voltage across the diode to a fixed voltage provided
by a three terminal regulator and a 10 turn pot. The wiper of
the 10 turn pot was connected to a single turn pot that
then provided the temperature setting. The two pots in series
were needed because the range of adjustment was very small
(the voltage across the diode varies with tempature, but the
change is small over the range we are interested in for
a heater controller.)

Hi,

2N3055: one-time trigger diode with abt. 160v triggering voltage
[had some ones of unknown state left from a PSU that blew one of 5
transistors, replaced them with MJ15003]

various, sometimes expensive components: firecrackers, smoke bombs,
lamps (most of the time unintended )

old EPROMs: Lamp.Find some pins with low resistance and apply .5-2A.

the IC/transistor that was broken and took you some hours to find the
trouble:
Get 1-5 large caps (like 12 000µF 350V), charge them, and apply the
voltage to the part with a very large relay.
LOUD!