Re: [Q900] PTT jack on the back
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Thanks for the details. There are some 5V relay modules that take a trigger signal and can be set to trigger if low or high. Then you'd need much less current through a pull up resistor. I have ordered such a module and intend to take the 5V source from the USB host socket. We'll see how it goes... Brgds, Edouard F4EXB On Thu, Jun 15, 2023, 19:55 N1COZ COZ <Callsign.n1coz@...> wrote: Yes! I simulated that chip in ltspice, and the highest value of the resistor to make a relay work is 1k. I got about 100mA thru ptt with 1k.? Plenty for a relay.? Now, the problem is with lowering the value. The bus that R81 is getting the voltage from might be affected, and other block circuits might be affected if too much current is drawn. So I thin think 910 to 1000 ohms should do.? |
Edouard Griffiths