Hi,
Does any one have any details, or know where to obtain them for making a water temp gauge, using a DVM and a thermistor as the sensor.
Thanks
Water Temperature Gauge
Moderator: RichardW
You dont say which of your cars - but either way the engine is the same type [;)]
All XU engines NOT fitted with a temp gauge have 2 thermoswitches for the temp warning lights. The idea is then to replace the HIGH temp switch (as to keep the lower temp early warning) with the sender for the gauge.
You must have a mating sender & indicator gauge, or calibrate these to each other yourself.
If you choose the latter, you must have some kind of an accurate temp reference on your running engine, like a DVM with a temp probe.
I have to say that this is beyond the average DIY'er, unless you are skilled with electronics circuits.
You may read more on this topic - even a complete description here : http://www.tramontana.co.hu/citroen/
All XU engines NOT fitted with a temp gauge have 2 thermoswitches for the temp warning lights. The idea is then to replace the HIGH temp switch (as to keep the lower temp early warning) with the sender for the gauge.
You must have a mating sender & indicator gauge, or calibrate these to each other yourself.
If you choose the latter, you must have some kind of an accurate temp reference on your running engine, like a DVM with a temp probe.
I have to say that this is beyond the average DIY'er, unless you are skilled with electronics circuits.
You may read more on this topic - even a complete description here : http://www.tramontana.co.hu/citroen/
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tomsheppard
- Posts: 1801
- Joined: 19 Dec 2002, 14:46
- Location: United Kingdom
- My Cars:
No Anders!This is easy.
Brian:
You need an LM35 chip from RS or Maplin. Be sure to spec the one that goes up to 110 degrees. (They are ok to 120.) Accuracy +/- 2 degrees.£5. Buy the cheapest yellow DVM that money can buy, don't spend more than £10. Shop around and you'll get one for £5.
Search for "LM35 Datasheet" on the net, to get the three connections. They draw minimal current so the + connection can go straight to the battery if you wish. - to earth and a screened lead carries the output to the DVM. Sleeve the three wires to the chip and cover the wiring with a good dab of non silicone bathroom sealant. leave it to dry. Abrade the stat housing until bright and glue the chip assembly to this, flat side of chip to stat housing with a minimum thickness of epoxy.
DVM reads 10 mV/degree Celsius so 1 volt = boiling point with the rad cap off.
The fan switch can be as much as 15 degrees below stat temperature, BTW.
I'd use the 2000 mV range and stick something over the last digit to get a reasdout in degrees.
Brian:
You need an LM35 chip from RS or Maplin. Be sure to spec the one that goes up to 110 degrees. (They are ok to 120.) Accuracy +/- 2 degrees.£5. Buy the cheapest yellow DVM that money can buy, don't spend more than £10. Shop around and you'll get one for £5.
Search for "LM35 Datasheet" on the net, to get the three connections. They draw minimal current so the + connection can go straight to the battery if you wish. - to earth and a screened lead carries the output to the DVM. Sleeve the three wires to the chip and cover the wiring with a good dab of non silicone bathroom sealant. leave it to dry. Abrade the stat housing until bright and glue the chip assembly to this, flat side of chip to stat housing with a minimum thickness of epoxy.
DVM reads 10 mV/degree Celsius so 1 volt = boiling point with the rad cap off.
The fan switch can be as much as 15 degrees below stat temperature, BTW.
I'd use the 2000 mV range and stick something over the last digit to get a reasdout in degrees.
Update,
Tom, had to get the sensors from Radio Spares as Maplins do not stock them any more.
Had to purchase a minimum of 5.
I could not get the display to read true, it dropped any thing from 6 to 10 deg c when the battery was loaded.
Did all sorts of things, additional screening, filters as spec sheet, the display would be stable untill I placed it in the engine bay, then it played up.
Any way to cut along story short, I fed it with a 9V PP3 battery, and that fixed it...
Did you have any of these problems.
Cheers
Tom, had to get the sensors from Radio Spares as Maplins do not stock them any more.
Had to purchase a minimum of 5.
I could not get the display to read true, it dropped any thing from 6 to 10 deg c when the battery was loaded.
Did all sorts of things, additional screening, filters as spec sheet, the display would be stable untill I placed it in the engine bay, then it played up.
Any way to cut along story short, I fed it with a 9V PP3 battery, and that fixed it...
Did you have any of these problems.
Cheers
I got hold of a wide range digital thermometer from CPC (I think), with LCD readout, powered by just an AA batt. I clamped the probe in place on the top hose & it worked well - not totally accurate, but I was able to record the normal operating temperature & keep an eye on it! This was on a BX. For some reason the thermometer went haywire after about six months & just gave totally random readings!
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martyhopkirk
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tomsheppard
- Posts: 1801
- Joined: 19 Dec 2002, 14:46
- Location: United Kingdom
- My Cars:
Hi Tom,
I do have a 5v regulated supply that I use to feed my voltage indicator. I did try this supply for the temp sensor, but it played up just the same.
I also tried it on both my BX's, and the results were similar.
The problem points to a voltage drop, but took the easiest route in the end, and pleased with the result.
Cheers
I do have a 5v regulated supply that I use to feed my voltage indicator. I did try this supply for the temp sensor, but it played up just the same.
I also tried it on both my BX's, and the results were similar.
The problem points to a voltage drop, but took the easiest route in the end, and pleased with the result.
Cheers