Hi guys, well I'm into a small project and am a little confused about the Volts needed to run certain computer fans, and/or other small units needed for my project.
The question is this, if I go to Dick Smith and purchase a small fan that runs with 12 volt power, is it OK to hook it up to one of my 13.8 regulated power supplies that already runs my set up.
I just tested a peltier cooler modual, and with the 13.8 regulated power supply and it got cooked in 3 seconds flat, yet $22.00 gone, but i do have another
It got that hot in 3 seconds that i actually burned my finger, as i was trying to feel for the hot and cold side .
Ok you experts on power, wattage, and amp's could you assist me please.
Yes, 13.8 will be fine for the fan.
It's also fine for the peltier.... what you did was subject it to thermal shock.
Peltiers should not be powered untill they are installed into a system with thermal loads.
Those 12 volt fans will run on 13.8 volts without too much bother but it might be a good idea to put a series resistor to limit the current a little. The 12cm fans draw a bit over 1/2 an amp at 12 volts so a 3.9 ohm 3 watt (or better ) series resistor may be advisable.
The 8 cm fans only draw about 1/4 amp so the series resistor would need to be 7.5 ohm (1 watt or better)
As for the loss of your peltier diode they are probably best fed from a current source not a voltage source. I think the nominal voltage is 15 volts at about 4 amps. This is about 60 watts that needs to be radiated from a heat sink on the hot side so if you wire it up and turn it on without a large heat sink and probably a blower it is going to get very hot very quick.
If you need to be exact with voltages, you can always get this Jaycar kit http://www.jaycar.com.au/productView...T&SUBCATID=588 if you need to run more than 1amp then you can sub the LM317T for an LM350T and drag upto 3A out of it (change the diodes to 3A as well).
I put 2 in a box and output 5v@1A and 7.5v@3A, you just turn the dial of the variable resistor to your output voltage.
The question is this, if I go to Dick Smith and purchase a small fan that runs with 12 volt power, is it OK to hook it up to one of my 13.8 regulated power supplies that already runs my set up.
Leon
Pretty much everyone has answered the question..except one..."if I go to DSE.."
DSE's stock of electronics components (fans) etc has declined badly in the last 3 or so years...forget them go to Jaycar.
Pretty much everyone has answered the question..except one..."if I go to DSE.."
DSE's stock of electronics components (fans) etc has declined badly in the last 3 or so years...forget them go to Jaycar.
It appears DSE are getting out of the parts business. According to someone in the know, Macquarie Centre have transferred most if not all of their stock to the Castle Hill store, and it looks like they are letting it run out.
Ah, so you guys are saying that i can't just test this modual on it's own buy hooking it up to the power supply on it's own, to test the hot and cold side, bugger it got so hot in an instant it nearly burnt the towel it was laying on, and smelled worse.
Leon, you can test it very quickly, but you can just install it, and then if it is heating/cooling the wrong way around swap polarity (positive to negative and vice versa). So there is no point in testing it and burning your towel and fingers again.
In my recent experiencewith Peltier units, they can be driven with either polarity - it really depends upon whether you are cooling or heating the thermal load. There is a nominal cold/hot side. If you are attempting to regulate the temperature of the load, then the peltier controller (if you are using one) with do both to maintain a constant temperature. It seems that in your case, however, that you just want to apply a fixed DC to the unit, but not necessarily have it actively controlled. That is OK, too.
You don't require a thermal load just to test the cooling/heating operation of the Peltier - but you DO need to supply the CORRECT POWER (Volts x Amps). Too little is OK, but too much is not!
What are the specifications of the Peltier you are using? There should be a nominal max power rating for it. If you exceed that, you might fry it - as it seems you have done. The Peltier you are using may not be rated for the 13.8V that you are using (and the resulting current) - it may require a much lower voltage.
It would be better to gradually increase the voltage (or current) from zero, up to its recommended operating point. Do you have access to a variable power supply - say, 0-15 Volts @ 4-5 Amps?
As for the DSE issue: It was once the bee's knees for hobbyists, but since Dick sold it, it has never been the same - particularly now.
