Saturday, May 17, 2014

9 Volt Regulator for Amplifier on Droid #2

Today I finally got around to a minor task for droid #2, regarding his sound system.

I'm using a Radio Shack audio amplifier that runs on 9 volts. Until now, I've been using a small 9 volt battery that resides inside the amplifier for its power. There are a number of disadvantages to this:

• The battery requires me to separately turn on and off the amplifier when I power up and down the rest of the droid.
• To get to the amplifier power dial, I need to remove the dome.
• I'm prone to forgetting it's on, thus running down the battery.

The solution is to use the amplifier's power adapter connection, that takes 9 volts DC in. Since my droid runs on a 12 volt power supply, I need to use an LM7809 voltage regulator to convert 12 volts to 9 volts.

The left pin is the 12 volt input pin, and gets connected to the 12 volt positive terminal strip. The center pin is ground, and gets connected to the ground bolt. The right pin is the 9 volt output pin, and gets connected to the positive input to the amplifier.

I added some thermal paste to the back of the regulator, before attaching it to the segment of aluminum angle bracket that I'm using as a heat sink.

Time to test it out in the droid!

It works! Now I can run without a battery in the amplifier, and use just a single on/off switch in the droid.


Chris Moody said...


I took my droid out to its first event last month (Wizard World St Louis), and the first thing I noticed was that my sound was too quiet to be heard in the crowd.

I'm using speakers attached directly to the CF Sound III system. If I volume it up too much, though, it seems to overload and I have to power cycle the CF III to get it to restart.

I was thinking of putting an amp in there between the CF III and the speaker. Is this what you've done? Or does droid 2 use something else for sound?

Victor Franco said...


Droid #1 uses the CFSound III with a speaker directly attached. For droid #2, I'm trying out Chris James' Stealth Controller, which uses the VMusic II and requires an external amplifier.

The CFSound III has a built-in amplifier, so maybe your speaker is too small? I'm using a 8-ohm, 0.5 watt speaker, and it has been working great for me, despite the low wattage rating. It handles a huge range of volumes from whisper-quiet to ridiculously loud. I use the same model speaker in both droids.

The speaker is a Philmore Model TS27. I see it in their catalog on page 136:

Hope that helps,

jasmine nile said...

thanks ...........

jasmine nile said...

thanks ...........