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VCO Build Help Needed

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VCO Build Help Needed

PostPosted: Sun May 17, 2020 9:18 am
by 1wildthing
Hi all, I received an Hearn Morley HMVCO1 chip from a friend and I would like to build an Eurorack module with it. As I didn't find any commercial PCB based on this chip I was thinking to stripboard it staring from the schematics suggested by the producer.
This is the schematic : https://sites.google.com/site/hearnmorl ... ects=0&d=1

As you can see it's a basic schematic so I would like to add attenuators to PWM and FM INs and also add a Frequency/Coarse tune Pot to the CV In.

I'm a newbie so I have to be honest, I'm really confused on how to do it.

I have a few question and I hope that you guys can help me:

1) As for PWM attenuator may I just insert a 100k potentiometer between PWM IN socket and the chip or it's better to use a resistor after the pot?

2) as for FM attenuator, a 100k pot in between IN socket and 2n2 cap is expected to work or I need to rebuild the circuit?

3) Could you please give me some advice on how to build and connect the frequency pot to this circuit?
Any hint would be really appreciated. Thanks in advance. :SOS:
Regards.

Re: VCO Build Help Needed

PostPosted: Sun May 17, 2020 9:40 pm
by RMCL
Have you seen the post dated 11 April 2013 in https://www.muffwiggler.com/forum/viewtopic.php?p=959109?

Re: VCO Build Help Needed

PostPosted: Mon May 18, 2020 10:37 am
by RMCL
You could also contact George Hearn via georgeleohearn@gmail.com explain what you are trying to achieve and ask if there are any application notes etc that he could send you that would help you with your project.

Re: VCO Build Help Needed

PostPosted: Mon May 18, 2020 6:11 pm
by 1wildthing
RMCL wrote:Have you seen the post dated 11 April 2013 in https://www.muffwiggler.com/forum/viewtopic.php?p=959109?

Yes I've already go through muff wiggler and I've found photos but no infos about what I need for my mods. :(

Re: VCO Build Help Needed

PostPosted: Mon May 18, 2020 10:25 pm
by RMCL
As I suggested try contacting George Hearn via georgeleohearn@gmail.com direct explain what you are trying to achieve and ask if there are any application notes etc that he could send you that would help you with your project