Custom Guitar Electronics

[Pauldf]

By the diagram it looks like the unit will take a pulse down the green wire and use that to drive it, all we need is a circuit that gives out a nice 12v square wave pulse. I'm pretty sure it can be done using operational amplifiers (maybe a 741?) with a large gain (Schmitt trigger) and a 12v supply. I'll have a look and see what I can come up with.

[Pauldf]

I have had a little look about, a simple op amp may suffice but will work on the frequency of the string as opposed to the volume of the sound. Looking at Wikipedia the bottom string is tuned around 81Hz, this equates to 4860 pulses per minute (which ought to show as 4860rpm.)
Is this too high?

[bickerstaff]

To be honest, it isn't necessary to do this particular one with a microphone or signal from the pickups. All this one needs to do is cycle from zero up the scale and back again, like the car is being continuously revved a bit.

If this can be done, please let me know as soon as possible what the cost will be. I have a target completion date for the build for end of 2nd week in December.

If anyone would like to chat with me about it, please give me a call 07920 093381.

Thanks

[Pauldf]

What does it do if you put the black wire to 0v and both red+yellow wires to 12v? It says on the sheet about it scanning but I don't know if it means once or continuously. If it only does it once what happens if you disconnect and reconnect the red wire?

[bickerstaff]

What does it do if you put the black wire to 0v and both red+yellow wires to 12v? It says on the sheet about it scanning but I don't know if it means once or continuously. If it only does it once what happens if you disconnect and reconnect the red wire?

I tested it by doing that. The red wire is a switched live, and the yellow is a permanent live. once connected, it cycles once as a test and then stays at zero. Maybe its possible to use the switched live in a circuit that powers us for say 5 seconds, and then switches off for 2 seconds, then switches itself back on again. I don't know, Im just a thick Mechanical Engineer with no understanding of electronics

[Pauldf]

Looking at the diagram the red is the switch live and the yellow is a permanent live, I'm wondering if a 2s on and 2s off pulse will work, ie if you hold the red wire onto + for 2s and then take it off for 2s and back on for 2s and so on, do you get the desired effect?

[bickerstaff]

Looking at the diagram the red is the switch live and the yellow is a permanent live, I'm wondering if a 2s on and 2s off pulse will work, ie if you hold the red wire onto + for 2s and then take it off for 2s and back on for 2s and so on, do you get the desired effect?

Yes, that seems to work. I can live with the display switching off for 2s.

[Pauldf]

Hi, I have managed to put a prototype 5s on, 2s off timer together, if you can pm me your address I'll send it to you

[Pauldf]

For info I put together a 555 timer circuit with on 5s and off 2s for the OP who is putting the guitar together.
I look forward to seeing the finished product!

[bickerstaff]

Thanks again for your help with this. Here is a pic of the completed guitar with the tacho fitted. It works well.