12 volt bulb question

[kendallizm]

I have a 12volt bulb from a car taillight. I have wired it into a yellow emergency light, kind of like an old police car light. I want the bulb to turn on and off quickly, can the prop1 board handle this?

[kendallizm]

I guess my question is can the prop board handle the bulb voltage directly without damage.?

[JonnyMac]

Voltage is not the problem, current is, and to be honest, I don't know how much current on of those taillight uses but as bright as they have to be I would suspect it's quite a lot.

What I recommend is that you build up a buffer circuit; it's easy and you can get the parts from RadioShack. 

Here's the circuit:



The easiest way to get from the Px.W terminal to the buffer is by using one of our 14" extender cables -- cut one in half and you have two connections.  The White wire carries the control signal, the black wire carries ground.

If the current is under an amp then you can connect the VX+ terminal in the circuit to V+ on the board and disregard the external power supply.

And here's a display from a few years ago that this circuit with a Prop-1.  See the headlight on the train? Well, that's an old car headlight.  I used random values with PWM to give the headlight a flicker effect.

[JonnyMac]

Just a thought after looking at the train picture: If you look closely you'll see that the smoke stack has a red glow to it.  This camer from a Prop-1 controlling a car brake light -- directly.  The trick is that it is a LED brake light.  Even the big ones consume less that 100mA which is fine for direct control.

So if you change from a filament style bulb to an LED bulb then you can connect directly to the Prop-1. 

Note: For safety you should always check the bulb current specs.  You want to keep the current under 250mA.

[kendallizm]

perfect thank you