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CGS88 Bi-directional Switch expecting bipolar control signal ?

CGS88 Bi-directional Switch expecting bipolar control signal ?

2016-02-20 by phijel

Hello


I am currently building this module (fully populated, but only the top section wired so far) and I am surprised to discover the control signal has to be bipolar to work (I was expecting it would with a standard 0-5V gate)

Is it normal ?

Would there be an easy way to make it work with gate signals ?

Thanks in advance for your insight !

ph


Re: CGS88 Bi-directional Switch expecting bipolar control signal ?

2016-02-20 by Ken Stone

It should work with a 0-5 v gate. It's detection point is controlled by the 8k2 and 10k connected to the 1M5 resistors. Decreasing the 82k further (or increasing the 10k) should raise the detection point higher. But first, make sure it's built properly.
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On Sat, Feb 20, 2016 at 11:10 PM, philippe@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Hello


I am currently building this module (fully populated, but only the top section wired so far) and I am surprised to discover the control signal has to be bipolar to work (I was expecting it would with a standard 0-5V gate)

Is it normal ?

Would there be an easy way to make it work with gate signals ?

Thanks in advance for your insight !

ph





--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS88 Bi-directional Switch expecting bipolar control signal ?

2016-02-20 by phijel

thanks Ken

I am sorry, wrong title, I build it as a triple Bi-di router, not a switch

And I've built it for 15V, so I placed 2x 4K7 instead of 2K2 and 2X 10K instead of 8K2. But I forgot to check the voltage between the 2 transistors emitters as you suggest. I did now, and it's at 15.12v

Any chance It killed the chips ?

Thanks

ph

Re: CGS88 Bi-directional Router expecting bipolar control signal ?

2016-02-20 by Ken Stone

Try 12k to start with. IF that doesn't help, go to 15k.

Cheers.

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On Sun, Feb 21, 2016 at 5:20 AM, philippe@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Please bear with me (it's only the 4th module I build, and the 3 first were working at first try ;-) )


What value would you suggest for the resistors in the voltage divider and in place of the second 8K2 (10K in my case) ?

ph




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS88 Bi-directional Switch expecting bipolar control signal ?

2016-02-20 by cg_synth

If you used a MC3401, perhaps it was damaged. That might explain why it wants a bipolar gate. If you used an LM3900, it will be okay. The CMOS chips? They don't like anymore than 15V. If they refuse to do what they are meant to do, replace them. If they behave, you've been lucky.

Re: CGS88 Bi-directional Switch expecting bipolar control signal ?

2016-02-21 by phijel

Well, I'm a bit puzzled here.

I realised increasing these 2 resistors value was in fact also increasing the voltage between the 2 transistors emitters :

with 2 X 12K -> 16.48V between the 2 emitters
with 2X 10K -> 15.12V
with 2X 8K2 -> 13.12V

so I went back to 2X 8K2 and it is now working fine !

But I didn't change the 2X 4K7 from the voltage divider, so I now have an hybrid version in regards to the values you recommend on the module page, but it works

Thanks

ph

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