Search found 269 matches

by Haralds:Werk
Mon Mar 30, 2020 1:33 am
Forum: Music Tech DIY
Topic: Scaled voltage reference with octave and semitone steps
Replies: 9
Views: 296

Re: Scaled voltage reference with octave and semitone steps

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...
by Haralds:Werk
Sun Mar 29, 2020 11:00 am
Forum: Music Tech DIY
Topic: Scaled voltage reference with octave and semitone steps
Replies: 9
Views: 296

Re: Scaled voltage reference with octave and semitone steps

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...
by Haralds:Werk
Sat Mar 28, 2020 4:04 pm
Forum: Music Tech DIY
Topic: Scaled voltage reference with octave and semitone steps
Replies: 9
Views: 296

Re: Scaled voltage reference with octave and semitone steps

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...
by Haralds:Werk
Sat Mar 28, 2020 11:41 am
Forum: Music Tech DIY
Topic: Scaled voltage reference with octave and semitone steps
Replies: 9
Views: 296

Re: Scaled voltage reference with octave and semitone steps

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...
by Haralds:Werk
Wed Mar 25, 2020 11:47 am
Forum: Music Tech DIY
Topic: Scaled voltage reference with octave and semitone steps
Replies: 9
Views: 296

Scaled voltage reference with octave and semitone steps

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...
by Haralds:Werk
Sat Mar 07, 2020 5:18 pm
Forum: Music Tech DIY
Topic: What PCB fabs are up and running
Replies: 5
Views: 272

Re: What PCB fabs are up and running

Just received my PCB's from Elecrow ordered first week in February.
by Haralds:Werk
Tue Feb 18, 2020 3:10 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

Re: Trapezoid VCO

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...
by Haralds:Werk
Tue Feb 11, 2020 4:37 am
Forum: Music Tech DIY
Topic: 15V to 12V Adaptor
Replies: 1
Views: 192

15V to 12V Adaptor

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 ...
by Haralds:Werk
Tue Feb 11, 2020 4:26 am
Forum: Music Tech DIY
Topic: The 2020 Show Us Your DIY Builds Thread!
Replies: 123
Views: 10712

Re: The 2020 Show Us Your DIY Builds Thread!

Finally I finished this one:
by Haralds:Werk
Tue Feb 11, 2020 2:57 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

Re: Trapezoid VCO

tardishead wrote:
Mon Feb 10, 2020 2:29 pm
Do the diodes have to be matched? Or nearly matched??
I have never matched them.
by Haralds:Werk
Mon Feb 10, 2020 2:10 pm
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

Re: Trapezoid VCO

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...
by Haralds:Werk
Mon Feb 10, 2020 8:33 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

Re: Trapezoid VCO

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...
by Haralds:Werk
Thu Feb 06, 2020 6:35 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

Re: Trapezoid VCO

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...
by Haralds:Werk
Thu Feb 06, 2020 2:38 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

Re: Trapezoid VCO

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,...
by Haralds:Werk
Wed Feb 05, 2020 11:22 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

Re: Trapezoid VCO

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...
by Haralds:Werk
Wed Jan 29, 2020 11:48 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

Re: Trapezoid VCO

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...
by Haralds:Werk
Tue Jan 21, 2020 9:42 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

Re: Trapezoid VCO

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...
by Haralds:Werk
Tue Jan 21, 2020 9:04 am
Forum: Music Tech DIY
Topic: Troubleshooting haraldswerk VC LFO
Replies: 11
Views: 640

Re: Troubleshooting haraldswerk VC LFO

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.
by Haralds:Werk
Fri Jan 03, 2020 4:02 am
Forum: Music Tech DIY
Topic: So I want to build a Clock Divider, what next?
Replies: 6
Views: 475

Re: So I want to build a Clock Divider, what next?

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
by Haralds:Werk
Tue Dec 10, 2019 11:17 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

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.
by Haralds:Werk
Mon Dec 09, 2019 2:39 am
Forum: Music Tech DIY
Topic: Troubleshooting haraldswerk VC LFO
Replies: 11
Views: 640

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...
by Haralds:Werk
Sat Dec 07, 2019 10:30 am
Forum: Music Tech DIY
Topic: VCO vs LFO design circuit considerations
Replies: 10
Views: 424

In most cases a switch and a additional cap should be suffice. Depends a bit on the architecture/waveshapers.
by Haralds:Werk
Thu Dec 05, 2019 11:33 am
Forum: Music Tech DIY
Topic: Trapezoid VCO
Replies: 73
Views: 5665

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...
by Haralds:Werk
Wed Dec 04, 2019 2:14 pm
Forum: Music Tech DIY
Topic: Troubleshooting haraldswerk VC LFO
Replies: 11
Views: 640

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...

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