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Output Halogen Lamp
Will a common 12v automotive relay provide a means of driving 55watt bulbs from a low power circuit?
I'm asking all of the electronic engineers' on this one. I simply want to drive a 12vDC 55watt halogen lamp from a circuit designed to drive a 12vDC channel with 400mA outputs.
Depends on how you mean this. If you mean can you use a 12V@400mA output to trigger the relay and then let the relay switch a 12V souce that is capable of driving 55W (roughly 5A) then the answer is yes. If you mean will the relay somehow make your 400mA source able to supply 55W then the answer is no. In fact, there is no reasonable way to make a 400mA source llight your bulb for any length of time by itself.
But if you meant the first interpretation, this could work if the coil requires <400mA. You have to be careful of the relay coil however. When current changes through the coil, large voltages develop and you could burn out your output. A safer way to do it would be to use a transistor and the relay and a diode.
Take your control output and run it through a small resistor (say 1K). The other side of the resistor goes to the base of a 2N2222 (you may have to pick a bigger transistor depending on the relay's coil current which will be 12V/the coil resistance in ohms; the 2N2222 can do about 100mA or so). The emitter of the 2N2222 goes to ground. The relay coil connects to 12V (the bigger 12V supply will do) and the other end of the coil connects to the collector of the transistor.
When the output goes to 12V, the transistor saturates and effectively brings the collector to ground (close enough) and the relay will pull in. The problem is, when you release it, you'll fry the transistor. To stop that put a common 1N914 or 1N4148 diode across the relay coil with the banded end pointing up to the 12V supply line. This will short the high voltages away from the transistor.
You can also use a FET like an IRL510 or similar if you need lots more coil current. The 400mA output could directly drive the gate (put a 1M resistor from the gate to ground to protect the FET against static). The drain goes to ground and the source would go as the 2n2222's collector did above.
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New Lights! American DJ Mystic LED & Microh LEDBAR - in HD!
Can you use normal halogen lighting instead of incandescent as basking light in Bearded Dragon Tank?
Obviously I know I have to get the basking temp right, and I know from doing a search that there are halogen lamps designed for vivariums, but from experience and working in an Electrical Wholesalers I know I can buy the incandescent lamps for 50p each rather than the rip off price of £3.50 from our local reptile shop, so wondering whether the halogen lamps they sell in reptile shops are just in a posh pack and whether I can buy halogen lamps from work for £1 each instead
At the end of the day I can't see why not - as its about the heat output with basking lamps - we already have reptile UV tube in situ so thats covered. Halogen lamps last so much longer and with a more narrow beam achieveable so I feel these would be better in our 2 tanks (and less easy to smash as we keep doing!!)
halogen FLOODS are good, very good actually for getting high temps at basking spots. you could get a 105f-115F basking spot for a bearded dragon with just one 30watt flood ,just raise/lower the "spot" towards the light.(or visa verse) and remember, halogen floods not halogen spots. halogen spot lamps provide too narrow a beam and burns become a real possibility. ive used 45 watt halogen floods to provide 165F basking spots for my monitors for years now.
