halogen lamps

[LucidGuppy]

How does one drive a high wattage halogen lamp?

[dacflyer]

Duh! just add the required voltage...just like you do a lightbulb...was this a trick question ?

[Bob Scott]

If it's rich, in a limousine, otherwise a regular SUV is OK.<p>CLAP CLAP CLAP

[cato]

It depends on how big a bulb it is. Are you working with a 1 quartz bulb or 2?

[jwax]

How high do you want to drive it?

[LucidGuppy]

I was talking about dimming and stuff like that. The lamp would be ones used in toaster ovens. I opened up the toaster oven to find a relay board. There are three control signals to the board. NMI HT and LT. The HT and LT go to two control fets that work on the relays to the toaster oven elements. I don't know what the NMI pin does. I'm wondering if its supposed to control a buck converter to power the relays to the elements?<p>The board outputs 5 volts from a 7805, but the relays are 12volt dc. I'm going to check to see what the dc voltages are like this weekend. The relay to one of the elements hums when I put the 5 volt signal to the HT line and then cuts out after a while. I'm wondering if the 12 volts supply is very noisy or isn't getting what it needs.

[LucidGuppy]

After looking at the circuit that I'm using to drive the halogen lamp - I have some more questions concerning 12dc 120volt ac relays.<p>The circuit's high volt dc supply is around 18 volts. The relay has a fet on the low side of the relay. When I turn on the gate the relay's coil can get 18 volts put across it. The relay dc rating is 12 volts for the coil and 120 ac for the switch. The element does not light up though and the relay does not conduct. What I would like to know is what happens when you put 18 volts across a 12volt coil relay. Does the relay require PWM to bring the 18volts on the relay closer to 12 volts?<p>Thanks very much.

[jwax]

If you're appliying 18 VDC to a 12 VDC relay, and it is not energizing, or its' contacts are not closing, you have a defective relay.
18 VDC to a rated 12 VDC coil is not a recommended practice, unless by design, if the duty cycle is short. In continuous duty, the relay will overheat.

[LucidGuppy]

I applied 13 volts externally when the board was powered down and I measured the relays resistance. The relay conducts when the supply is 13 and not 18. I think I'm gonna cut the trace and insert a 7812 regulator circuit to bring the voltage down.

[LucidGuppy]

Yeah after working on it and only applying the 12volts to the relays - they're busted. Does anyone know of websites that have tips for wiring ac electrics (safety - standard practices)? I'm gonna have to build my own relay board.<p>Thanks