Ken, take a bow for offering a likely solution to the problem. Also, if I can hijack 6705's thread for a moment, your own design amplifier sounds somewhat intriguing. Any chance of a peek at your ckt diagram, or maybe even a photo?
That's if I'm not being nosy, of course.
Hi everyone that replied,
This has indeed opened a "can of worms". First of all, John S has mentioned the Maplin's amplifier modules. I went this route first with their Higher Wattage version amp and had severe buzzing. This was traced to the output to the speaker being between positive voltage and signal, rather than the conventional earth and signal !!. This necessitated the isolation of the supply earth connections as there was an earth loop hum created.
After days of work and thought, I scrapped this method and cut out the amplifier circuit board from a scrapped Yamaha keyboard (my old trade) and wired this into the boat. (see picture below)
The Action power supply board was then cut to isolate the supply voltages from each other and supplied with separate battery connections. (see second picture ). The third battery is to give me a choice of 18 volts to the motors for surfing.
Bluebird is right on the nose with the BEC suggestion as this connection contains the linking earth wire which causes all the problems.
It is truly a maze of problems when you mix analogue and digital circuits with electric motors all in the close proximity of a boat. I really do not know the best way to achieve what you are after Russ as the addition of 'sparky high speed motors' only confuses the mix.
Try the isolation route and please let us all know.
Ken