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Better circuit choices for Silent Way AC Encoder
MUFF WIGGLER Forum Index -> Expert Sleepers Goto page Previous  1, 2, 3, 4, 5, 6, 7  Next [all]
Author Better circuit choices for Silent Way AC Encoder
realitycontrol
I've spent some time crafting both the half wave rectifier and the voltage doubler using the diagrams on page 1.

Using an Echo Audio Layla interface and the AC encoder plugin I get a max of 0.13V with the half wave rectifier and 0.26V with the voltage doubler.

These values seem to be way off what other members have been able to get.
Does anyone suspect an issue on my interface or perhaps with my interpretation of the diagrams?

I have tried the following capacitors;
http://www.maplin.co.uk/p/01f-63v-85c-electrolytic-capacitor-au07h
http://www.maplin.co.uk/p/022f-63v-85c-electrolytic-capacitor-au08j
http://www.maplin.co.uk/p/1f-63v-85c-electrolytic-capacitor-au09k

And the following diode;
http://www.maplin.co.uk/p/1n4148-150ma-switching-diode-ql80b

Cheers.
os
Is the interface output actually turned all the way up?

Maybe post a photo of what you've built? Else it's hard to know if you've done it right.
realitycontrol
oops Computer audio was down.

Upon turning up the master volume I'm getting around 7V from the half wave rectifier, interestingly enough I am getting the same value when using just the DC plugin and a floating ring cable.

However, both values slowly go down whilst taking a reading with a multimeter, after about 10 seconds it will be <5V. I believe I read a post earlier where someone else was experiencing the same issue, will see if I can find it.
realitycontrol
Turns out that the earlier post which I thought may hold the resolution to my problem was in regards to using the AC Encoder plugin.

I am using the AC encoder after the DC plugin along with the half wave rectifier cable and yet the voltage reading from the output just won't stay still. It generally starts around 7-9V then gradually drops.

This is the first time I've attempted to follow an electronics diagram so I presume my handywork is at fault.
I'd appreciate if someone could take a look.



For clarity;
TRS - Tip - A1
Diode - B1 to C6
Red Cable - A6 to A12
TS - Tip - B12

TRS - Shield - A3
Capacitor - B3 to B6
White Cable - F3 to F15
TS - Shield - E15
os
That looks OK. When you say it gradually drops, what does it drop to? Is that with something (e.g. a synth) connected at the TS end?
realitycontrol
Cheers for taking a look.

It takes a while, but eventually it drops to somewhere between 2 and 3 volts.
This is all whilst the TS end is not connected to anything other than a multimeter.
os
Try it actually plugged into something. A multimeter doesn't really present a realistic load on the circuit.
realitycontrol
I've basically been comparing the output from silent way againts a multimeter reading from the pitch out on the Microbrute which provides me with a stable voltage.

Plugged it into the X input on a Disting (Mode 4C) and experience something similar to the readings I was getting.

Video available here: https://youtu.be/qcfNNn_Xvvg
os
Which version of disting is that? If it's a really early one, you might want to try putting a largish resistor (say 100k) across the TS output.
realitycontrol
It's a mkII.
Cheers, I'll give that a go this evening, delivery of resistors from RS arrived today.
realitycontrol
I get the same result. Popped the resistors ends into C13 and D15 on the above breadboard.

Had a go with a Focusrite Scarlett 2i2 this morning. The output is voltage is much lower yet it still does not stay stable whether it is plugged into the disting or not.

You've mentioned elsewhere that one could expect this sort of a result if the interface is not DC coupled and one is not using the AC encoder plugin. Is there a chance that there is an issue with the way I am using the AC encoder? It's running on Ableton Live 9 64bit, Win 7 64 bit and it's if that makes any difference.

Cheers.
os
It's possible. Why not post a screenshot of your setup in Live?
realitycontrol
Sure;

os
That looks OK, assuming you're using output 7 on your audio interface.

Are you sure you have the right connections on the TRS jack? It's hard to see from the photo which part of the socket will make contact with which part of the plug.
realitycontrol
Thanks Os.
Assuming that I'm using output 7 would be correct.
Just used a multi-meter to confirm the connections, Tip is going into A1 and Shield is in A3 on the breadboard.
os
Grasping at straws now, but what sample rate are you running Live at?
realitycontrol
I was running live at 44.1 kHz, the sound card was running at 96kHz.
Have had a quick play around and get a similar result when both the DAW and Soundcard are set to the same sample rate.

Is there a particular sample rate which I should stick to for any future tests?
os
Quote:
I was running live at 44.1 kHz, the sound card was running at 96kHz.

Is that even possible?

Let's stick to 44.1 system-wide for now.
realitycontrol
It was outputting sound just fine! But yeah, bit of a mistake on my part.

Right so I finally think I'm making some head way.
I put together the bridge rectifier circuit and I am able to get a steady voltage of up to 19 volts out of it.
One little niggle though; the voltage takes a while to drop, going up in voltage is instantaneous and solid but I've got a constant slew when the notes are falling.

Any wise suggestions?

Edit: Resistor over the outputs, you've previously answered that question for me.
os
So you're good now?
realitycontrol
Yeah all good, thanks for sticking with me.
pwranml
What capacitors and diodes should I use? Going to try the original circuit to keep things as simple as I can. I have a Focusrite Saffire 6. Is it possible to take advantage of the rca outs as well? Also might be a dumb question but what about a laptop headphone jack?
os
Start with a 1uF capacitor and go up or down from there. Any diode will do but the 1N4148 is a popular choice.

The RCA outs will probably be very low level, but you could give them a go. Likewise the laptop headphone socket.
scott.lepore
Can anyone tell me if the input to SW, used to calibrate the pitch CV out, needs to be an AC cable, or is it a regular audio cable. (FWIW I'm using a Focusrite 18i20 and an 8i6.)

Thanks!
os
Regular audio.
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