I'm repackaging my old turret-board Transcendent Grounded Grid and want to delay the HV to allow the tube warm-up and keep the output muted until HV is up.
It has two hv supplies: +200VDC and -200VDC. Those and the heater supply are all fed by their own secondaries from a single transformer. So if I delay HV, it has to be done on the secondary.
I have 4 channel relay board connected to an Arduino. The relays are rated for 10A 250VAC.
ANMBEST 2PCS 4 Channel 5V Relay Module with Optocoupler High or Low Level Trigger Expansion Board for Raspberry Pi Arduino
relay 1: Secondary 1 to NO - COM to +200VDC PSU
relay 2: Secondary 2 to NO - COM to -200VDC PSU
relay 3: Signal Output 1 NC - COM to ground
relay 4: Signal Output 1 NC - COM to ground
Relays 1 and 2 come on at 30 sec, relays 3 and 4 at 40 sec. I have a basic sketch that seems to work.
Am I missing anything?
It has two hv supplies: +200VDC and -200VDC. Those and the heater supply are all fed by their own secondaries from a single transformer. So if I delay HV, it has to be done on the secondary.
I have 4 channel relay board connected to an Arduino. The relays are rated for 10A 250VAC.
ANMBEST 2PCS 4 Channel 5V Relay Module with Optocoupler High or Low Level Trigger Expansion Board for Raspberry Pi Arduino
relay 1: Secondary 1 to NO - COM to +200VDC PSU
relay 2: Secondary 2 to NO - COM to -200VDC PSU
relay 3: Signal Output 1 NC - COM to ground
relay 4: Signal Output 1 NC - COM to ground
Relays 1 and 2 come on at 30 sec, relays 3 and 4 at 40 sec. I have a basic sketch that seems to work.
Code:
#define relay1 7
#define relay2 6
#define relay3 5
#define relay4 4
void setup() {
Serial.begin(9600);// setup Serial Monitor to display information
pinMode(relay1, OUTPUT);// connected to Relay 1
pinMode(relay2, OUTPUT);// connected to Relay 2
pinMode(relay3, OUTPUT);// connected to Relay 3
pinMode(relay4, OUTPUT);// connected to Relay 4
Serial.println("wait for 30s");
delay(30000);
digitalWrite(relay1,HIGH);// turn relay 1 ON
Serial.println(" relay 1 ON");
digitalWrite(relay2,HIGH);// turn relay 2 ON
Serial.println(" relay 2 ON");
delay(10000);
digitalWrite(relay3,HIGH);// turn relay 3 ON
Serial.println(" relay 3 ON");
digitalWrite(relay4,HIGH);// turn relay 4 ON
Serial.println(" relay 4 ON");
}Am I missing anything?
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He appears to be switching "AC", before the rectifier. I agree this might even be worse than switching straight DC.
AC will "pause" 120 times a second. Any arc will go out.
Straight DC above a few volts, the arc may never go out, unless the contacts are designed with blow-out or deflection features.
Switching the input to a rectifier and capacitor can be a HUGE turn-on current. The kind of thing that other builders go to great lengths to avoid.
Looks fine to me. relays rated for 250 and you're switching 200. I don't get the DC above a few volts comment. Nearly every relay has DC ratings for contacts though usually never as high as the AC rating. Relays switch heavy loads constantly for many years. I finally had to replace a few in my 30+ year old garage door opener.
Thanks. The secondaries are only 120VAC so well below max. The PSU is a voltage doubler.
Yes. You should short the output at power off before the B+ has gone. And
don't bother with delaying B+ .
False. But long periods of filement AND no B+ may cause "cathode poisoning" where an isolated layer is built in the cathode surface. ( long means hours )
B+ applied at power on is no danger for tubes operating below 1000 volt.
I've seen schematics where the output muting is a relay connecting the output to ground. This must be on the output side of the coupling cap of course. This means you aren't sending signal through a relay contact during normal operation. You could use a signal relay instead of a power relay.
I'm in the "no need to delay B+" camp on this one.
I'm in the "no need to delay B+" camp on this one.