AS3340 square low level + offset

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yentzee
Common Wiggler
Posts: 98
Joined: Tue Jul 21, 2020 11:22 pm

AS3340 square low level + offset

Post by yentzee » Wed Jan 13, 2021 4:57 pm

Hi,
I am trying the circuit on Eddie Bergmanns site for the as3340. Tri and saw look fine, square however has a very low level and doesnt seem like a real square. Did anyone have this issue before or knows which pin (-s?) Are not supplied correctly for such a behaviour to appear?

Thanks for helping

Jens

pjbulls
Common Wiggler
Posts: 111
Joined: Tue Feb 04, 2020 5:26 pm

Re: AS3340 square low level + offset

Post by pjbulls » Thu Jan 14, 2021 3:02 am

Did you install the Zener diode ZD1 the correct way around? No other design I've seen has that, they usually handle scaling and offsetting the square differently. Still, seems a likely culprit.

There's also a purported difference between the CEM3340 and the AS3340 in their pull-down requirement for the pulse out, 10K for the CEM and ~51K for the AS. The schematic seems to be specifically for the Alpha chip, I have no idea if that even really makes a difference.

yentzee
Common Wiggler
Posts: 98
Joined: Tue Jul 21, 2020 11:22 pm

Re: AS3340 square low level + offset

Post by yentzee » Thu Jan 14, 2021 4:16 am

I took the resistor values into account and put the zener in that way that it serves as a current protection letting elektrons flow if 10V is exceeded, at least that is what I think it is doing but I will check again. Thanks for helping :)

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