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Show us your square wave

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Insatman:
sort of coaxial...it's a COTO 9000 series coaxial shielded relay.  In the low voltage version the relay is soldered as close to the BNC connectors as I could manage.  In the slightly slower high voltage version the relay is connected using a socket for easy replacement.  This increases the inductance a bit. 

When I swapped out the coaxial version for a non-coaxial version the rise-time did not change much as the ground is also carried across by my socket arrangement.  I built the larger version with a socket so I could experiment with different relays.   What I also found out is that over driving the relay coil helps with contact bounce. 

I also found that these particular COTO relays can't handle the 1000kV charge voltage I was hoping to use.  Still, 100V into 50ohms is more than enough for the work I am doing. 

Insatman:
You can get a few 10's of Hz out of these relays.  I set mine to run at single shot or ~10Hz switch selectable.  I tested it up to 30Hz with no difficulties.  COTO claims up to 1x10^9 operations, but I think switching 50ohm circuits will likely degrade this significantly.   I have yet to wear one out however.

MrW0lf:
Keysight U1282A 2.4kHz, 50% duty into 600 ohms.





Otherwise nice but hydraulic press channel dude should deal with these parasitic spikes.

RedDogAlpha:
This is a great insight for someone green! Thanks for the post.

qu1j0t3:
1 kHz and 1 MHz generated by Arduino Duemilanove (program below); a little interference from 16MHz device clock is clear in the 1MHz trace. Rise/fall ~ 19ns.

Scopes: Tektronix TDS 460A (display in "High Res" mode) and HP 1741A (Conv mode).


--- Code: ---void setup() {
  // for ~ 1 kHz output on PWM pin 9 (OC1A)
  pinMode(9, OUTPUT);

  TCCR1A = (1 << COM1A0); // toggle OC1A on compare match
  TCCR1C = 0;
  TCCR1B = (1 << CS12) | (1 << WGM12);  // clkIO/256 prescaler; clear on timer compare
  OCR1A = 30; // ~ 1 kHz
  TIMSK1 = 0; //(1 << OCIE1A); // set output compare A match interrupt enable

  // ~ 1 MHz on OC0A (digital pin 6)
  pinMode(6, OUTPUT);

  TCCR0A = (1 << COM0A0) | (1 << WGM01); // toggle OC0A on compare match; clear on timer compare
  OCR0A = 7;
  TCCR0B = (1 << CS00); // no prescaler
}

void loop() {
}

--- End code ---

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