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Duplicate potentiometer with sonar


Hi everyone,

I am quite of a newbie in electronic but I learn quickly, here is my project:

I have a small amplifier wich is commended by a potentiometer. For some reason I would like to duplicate this potentiometer with a sonar (such as this). The potentiometer is a B50K (as this one apparently) so that if you turn it completly counterclockwise it switches the amplifier off. It's a logarithmic potentiometer I think.

    -First, the idea is that I could use the sonar or the normal potentiometer equivalently (parallel assembly?)

    -Secondly, I think I'd set a small switch (wich one?) that makes the sonar inactive so that the device is commanded with the normal potentiometer only.

    -Finally, the way I would like the sonar to work is as follow: if you pass your hand just above it (at around 5cm) it acts as a switch (on/off), but if you putt your hand higher (from 20 to 60cm) you can adjust the volume by moving your hand verticaly.


The main question is what PLC (picaxe I guess) do I need? I'll upload a diagram of how I plan to make it soon, if anyone want to drop an eye on it... :)

Thank you in advance.


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Hi everyone, I think this time I've got it right,

I finally choose a 14M PICAXE in stead of the 08M PICAXE because as birdmun said, I need more than 8 pins. I connect the PLC to the digital pot as they did in the blog birdmun gave me.

@Birdmun: Do you think the 14M PICAXE and the code lines on the blog mentionned above will solve the missing SPI problem?

@Antonio: You say it will be complicated to go back to the analog world but isn't it the job of the digital potentiometer? Although I will need to read the MCP42XXX manual

I really think this is the right diagram, so if anyone want to drop an eye on it... Because I think I am going to order the components and a stripboard :)

diagram 1.0

Well let's say "source in" is source out actually: the source we will have to amplify. And "Amp out" is Amp in: these two pins go back to the amplifier, bringing the amplified signal.

Thank you for your advices and opinions


What works on a 08M should work on the 14M.