For the delay start of HV on the GRHV boards, what value resistor should I use for driving the CPC1117N Opto using 15V? The spec sheet was unclear on this, but I was assuming I should add a 3K or so resistor (?).
EDIT: Well, to answer my own question, I was able to find the forward voltage drop of the diode in the CPC1117N using my meter. It is 1.2V. So with 15V supply, that leaves voltage of 13.8V to get rid of. The turn on amps for the 1117N is 1ma min to 50ma max. Assuming 10ma as a safe target, I get R=13.8V/.010A=1.38K resistor. Since 2.2K is a common value, I will go with that which will provide about 6ma current to trigger the opto relay.
EDIT2: Yes, these values worked fine. Here is a crude drawing of the circuit. I am measuring about 5ma to the CPC1117N input, which is about what I wanted. A 3K resistor would probably work just fine as well and would lower the current even more to the CPC diode. I am using THIS device, 12V version, from eBay as the timer. It works great for this application and is cheap. I have it set for delay on of 60s. You can also put jumper on S5 on the device and it will provide the VCC without the additional wire from Vcc to relay COM.