Sunday, April 08, 2012

Installed Receiver Battery Eliminator

More unanticipated work on droid #1.

For quite a while I've been wanting to eliminate the separate 4.8 volt battery that powers the receiver. I've had the separate battery and on/off switch since my droid was born, and it's a bit of a hassle to have to recharge that battery separately, and always flip two power switches (one for the receiver, the other for all the remaining electronics that run on 12 volts).

This past week I went to Radio Shack and picked up some LM7805 voltage regulators, which can take up to 37 volts and step the voltage down to 5 volts. This 3-pin regulator can handle 1 amp. It's just a matter of hooking the input pin to the 12 volt power supply in my droid, hooking the middle pin to ground, and hooking the 5-volt output to the receiver.

I swung by Mike Senna's house yesterday before his Game Stop gig, as he has filter capacitors that help filter out spikes in voltage that should be soldered to the voltage regulator. Mike added these two small components to the regulator.

A little fire sets the shrink tubing in place.

Today I had time to install everything. The first step was to make sure the regulator was doing its job. 12 volts in, 5 volts (well, 4.97 volts) out.

The regulator works by turning that excess voltage into heat. Thus, I cut a small piece of aluminum bar to use as a heat sink.

I drilled a hole for mounting the regulator, and the whole assembly into the droid.

Let's see... where to put it? Here's a spot on the vertical plank where there is a little room. We'll drill a pilot hole here.

And on it goes.

So far so good, one power switch now turns the whole droid on and off, and I no longer need the receiver battery. Having said that, I'm going to continue to provide the option to use the receiver battery (and backup AA batteries), just in case I need them for some unexpected reason.

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