Batboard

I'm wanting to wire a volume pot inside a standard Motorola 13 watt external speaker and plug it into the 16 pin connector on a radius mobile. I know motorola radios can be picky about ground when it comes to the external speaker leads, what is the easiest way to wire a volume pot with an external speaker and not fry the audio circuit in the radio?? I'm trying to use an external speaker along with the internal speaker, the external speaker is going to be just on the other side of the wall from the radio in another room and i would like for it to have its own volume control right on the speaker so they can turn it down or completly off if need be.

Mike

A 50ohm pot across the ext spkr out leads (15 and 16 if I recall correctly). Spkr connects to wiper and common (pin 16 IIRC).

I tried both a 50ohm and a 100 ohm and i get full volume at the max point of the wiper, but when i go to decrease it, it cuts the speaker off all together.

You may have log pots rather than linear pots. You need a linear pot.

They shoud be wirewound pots, I have been using 500 ohm 5 watt (i think) wirewound in series with my external speakers.
A carbon pot will not do it, I am not even sure a carbon pot has a wattage rating.

Other problem you may have once you get this working is someone adjusting the volume on the radio which will also change the volume on the external speaker

Where would i get a Wire Wound pot? I am aware that if the main radio volume gets turned down it also affects the external speaker, but they hardly ever adjust the volume once they get it set on the main radio.

You might consider an L-pad. These are designed for adjusting speakers.

http://www.parts-express.com/pe/showdet ... er=260-248

That's a 15 Watt one, they have larger ones too.

At our shop we use a 15 ohm pot across the speaker leads (1 and 15/16) and the speaker goes from 1 to the wiper of the pot.

Side note: some speaker/pot combinations have enough room where you can drill a hole centered in front of the speaker and mount the pot there. The Micor/HSN9236 square plastic speaker is one of them.

Radio Shack carries L pads if you prefer to go that route.

Bill_G wrote:Radio Shack carries L pads if you prefer to go that route.

Do they still carry them? I couldn't find them on the website, all I could find were the transformer type volume controls which are more expensive and also much larger.

jackhackett wrote:

Bill_G wrote:Radio Shack carries L pads if you prefer to go that route.

Do they still carry them? I couldn't find them on the website, all I could find were the transformer type volume controls which are more expensive and also much larger.

I could be wrong. I haven't checked in a while. It was one of the few things they sold that was actually useful.