If you are doing it yourself have a look here: https://www.haraldswerk.de/Filter/NGF_L ... adder.html

Wow!!!! Excellent. Sorry to tear half your circuit up. Also remember that even with 0.1% resistors the error of an inverter can be 0.2%, i.e. one resistor +0.1% and the other -0.1%. So why have a precision inverter on the reference and then go through two 0.2% stages? You can lose IC4A by reversing...

Interesting module. I'm curious why you don't use the REF02 (and it's inverter) to bias the semitone switch as well? You just need to replace the 100k resistors with 40k and everything else stays the same (or replace the 40K+15k with 54k9 resistors, plus trimmers if you really care). It's easier th...

Interesting module. I'm curious why you don't use the REF02 (and it's inverter) to bias the semitone switch as well? You just need to replace the 100k resistors with 40k and everything else stays the same (or replace the 40K+15k with 54k9 resistors, plus trimmers if you really care). Yes, you can d...

Really good to see - I made something some years back but was never quite sure of its accuracy. It would be good to DIY something new for my work bench. Does it really not require any trimmers? Maybe I got carried away worrying about trimmers & offsets. No trimmers needed. But you have to select th...

This module provides high precision CV outputs in 1V (octaves) and 83,3mV (halves) steps. The 1V output goes from -5 to +5V. The 83,3mV steps goes from -5 to plus 5 steps (halves). This module is thought for all who are missing octave switches in some modules. Especially in VCO. With this module you...

Just received my PCB's from Elecrow ordered first week in February.

I thought you still use the BF256B as mentioned in your earlier post. So if you have the right FET check the resistor values. And have a look at the diodes and trimmers. Last resort is swapping the working FET against the not working so you can deduce that the FET is bad.. Right so I bought a new b...

From time to time I want to integrate a 12V Eurorack module in my 15V banana setup. So I needed a 15V to 12V adaptor. Nothing spectacular. Just from the datasheet. Specs and features • Input +/-15V DC (or higher) • Output +/-12V DC The documentation and the Gerber files for download can be found in ...

Finally I finished this one:

tardishead wrote: ↑

Mon Feb 10, 2020 2:29 pm

Do the diodes have to be matched? Or nearly matched??

I have never matched them.

Get the specified BF245B. They are still available if you do some search. I am using BF245B. I must have a bad one I thought you still use the BF256B as mentioned in your earlier post. So if you have the right FET check the resistor values. And have a look at the diodes and trimmers. Last resort is...

Compare the input signals of the sine shaper at IC1A pin14 and IC1C pin1. If they are equal try replacing the FET. Are you running it at 15V or 12V? I have no BF256B around, so I can not test it. I tried to trim the second sine shaper again tonight but with no better success. It is still short of c...

Yeh I'll look into that. This is a really good VCO. The more time you spend with it the more you find. At first I thought the quadrature outputs were only useful for LFO duties but in audio rate - adding and subtracting the waveforms creates a lot of really interesting wave shapes. I am glad that y...

Shape - One circuit has a much better shape than the other after trimming for best possible shape. I will try another BF256B. Compare the input signals of the sine shaper at IC1A pin14 and IC1C pin1. If they are equal try replacing the FET. Are you running it at 15V or 12V? I have no BF256B around,...

Strangely one of the sine shaper circuits does not work as well as the other. Would that be the result of an unsuitable FET? Is it necessary to choose the FETs out of a batch perhaps? Or perhaps badly mismatched 1n4148 diodes? I thought I had used 1n4153 diodes which are better tolerance 1n4148s bu...

I am using a socket and put the tempco above the socket. Socket - tempco - SSM2220. So the tempco is below the SSM but above the socket. Is it a good idea to put heat transfer compound between the SSM2220 and the Tempco? Or is that overkill? I don't know. I don't have the means to do the measuremen...

I am building the Trap VCO and Waveshaper boards from Harald. I thought I would document some of my experience in case it will help others. Thank you. I am always happy to hear from other builders. Every feedback is welcome. This keeps me going and helps me to improve my designs and my website. The...

I am always happy to hear from other builders. Every feedback is welcome. This keeps me going and helps me to improve my designs and my website.

The edges from the triangle are rounded off by pushing the OTA over his limits. So, as said above, turn up the volume.

If you want to go digital have a look here:

Dividing 2..8:
https://www.haraldswerk.de/Gate_and_Tri ... r_2_8.html

Dividing with prime numbers 11..31:
https://www.haraldswerk.de/Gate_and_Tri ... prime.html

Sorry no soundfiles yet. The trapezoid wave sounds somewhere between triangle and sine. What makes this VCO interesting are the quadrature outputs and of course mostly the through zero capability. I highly recommend the waveshaper to get all the other waves as well.

Nothing wrong here. 40Hz max is perfect for a LFO. The emphasis is on Low. The fault was on my side. I forgot to correct the figures from 700 to 40Hz on my website when I changed the value of the capacitor. I wanted to have a LFO which can go very slow on the low end. Doing so you'll lose on the hig...

In most cases a switch and a additional cap should be suffice. Depends a bit on the architecture/waveshapers.

I have a new version online now. With thanks to Don Tillman I could simplify the schematic. The level shifting in the address lines to the DG409 is removed and I switched to a two capacitor design. Some part values are changed as well. Docs and Gerbers are updated. https://www.haraldswerk.de/VCO/Tra...

Thanks for the hints! I've checked C3 and tried to feed CV inputs but no luck. I'll put this project on the side for a while. It's too frustrating to put more hours into this :) Earlier I've succesfully build Bastl Kastle so I'm thinking of making multiple Kastle LFOs instead of these. Remove the c...