[Wolfesmetalfab]

Is a relay needed with the bob campbell BOB, or can the board control that on its own? I have a cutmaster 51 that has two terminals for connecting for machine use.

see link for pic http://www.cnczone.com/forums/showthread.php?t=48868

I am familiar with that, but need to know if i can just connect those to terminals to the bob, or if I need a relay, and if so, like a regular 12v automotive relay using the 12v out on the board?

any of these work?
12 VDC N.O. RELAY
12 VDC SPDT 30 AMP RELAY
New in Box Solid State Relay SSR 24-480V AC, 25A


Thanks
Brian =)

[bharbour]

The Combo+ BOB has several uncommitted relays on it (3 I think). I have used them on milling machines and used the relays for spindle run/stop, direction and coolant pump control. There is a 4th relay that is controlled by he charge pump on the BOB. If you are not using those relays for anything else in your system, they should be fine. I think the relays are rated at an amp or so and should be fine for a control signal. I can't speak on any of their other models, but the information should be in the docs that are freely downloadable for his boards.

Bob

[Wolfesmetalfab]

what relay should i be looking for if i purchased it separately? I dont need all the extra relays, and $50 I can beat by along ways by just buying the relay I need, but I dont know exactly what to look for.

The bob output voltage is 12v, and the plasma when reading dc volts across the 2 machine switch terminals, it is 11 volts.

I read that i want a solid state relay, and i am not familiar with these. does it need to be, or just a standard relay?

[bharbour]

what relay should i be looking for if i purchased it separately? I dont need all the extra relays, and $50 I can beat by along ways by just buying the relay I need, but I dont know exactly what to look for.

The bob output voltage is 12v, and the plasma when reading dc volts across the 2 machine switch terminals, it is 11 volts.

I read that i want a solid state relay, and i am not familiar with these. does it need to be, or just a standard relay?

I looked at Cambell's "Combo" break out board and it specifies solid state relays for the relay outputs. This means that the relay outputs only have drive for solid state relays which need at most about 30milliAmps to switch on. The first two of your choices in the first post will be way too much load to drive directly.

All of the solid state relays that I have used have an opto-isolated input and the output varies from transistors to triac's depending on whether the relay is designed for DC or AC loads. Solid State Relays need to be selected based on what load you are driving with them.

I looked at the service manual on the Cutmaster 51 and could not find any specifaction on what the torch switch circuit actually drives. It is probably a 12V DC low current control signal, but it might be controlling a relay or have some wierd AC circuit that would not show up on a voltmeter. Without the machine in front of me, I would say spend the extra $50 for the BOB with actual mechanical relays.

Good Luck,
Bob

[Wolfesmetalfab]

I asked Bob Campbell, and he referred the question to james cullins, and james answered

"The THC 300 has a relay for firing the torch. You can use Bob's breakout board and the THC 300 that is all you need. Check out my web page www.soundlogicus.com You can download the manual, install program and other useful files."

I may use the thc300, but want to try it without first to see if I am happy without it.

the cutmaster 51 does measure 10.85 volts across the two torch trigger terminals. It draws .02 amps on activation, when torch is arcing, it switches to -.05 on the multimeter.

Is there a way of testing how much current is ok on the bob ouput for the relay?

I have a relay sitting infront of me, and when tested, it pulls .16 or 160 milliamps. Is this way to much for the BOB output you think? It clicks, so it is not solid state, I am just having a hard time locating a proper solid state relay. In the THC300 manual, it says that when testing, you will hear the relay click, so it is not solid state, why is it ok for them to use, but not me, im confused?

Edit: Something like this may be the ticket...

http://www.mouser.com/Search/Product...BP7tkZuA%3d%3d

The TS3R1G or TS3R2G as shown on the data sheet seem good.

[bharbour]

I asked Bob Campbell, and he referred the question to james cullins, and james answered

"The THC 300 has a relay for firing the torch. You can use Bob's breakout board and the THC 300 that is all you need. Check out my web page www.soundlogicus.com You can download the manual, install program and other useful files."

I may use the thc300, but want to try it without first to see if I am happy without it.

the cutmaster 51 does measure 10.85 volts across the two torch trigger terminals. It draws .02 amps on activation, when torch is arcing, it switches to -.05 on the multimeter.

Is there a way of testing how much current is ok on the bob ouput for the relay?

I have a relay sitting infront of me, and when tested, it pulls .16 or 160 milliamps. Is this way to much for the BOB output you think? It clicks, so it is not solid state, I am just having a hard time locating a proper solid state relay. In the THC300 manual, it says that when testing, you will hear the relay click, so it is not solid state, why is it ok for them to use, but not me, im confused?

Edit: Something like this may be the ticket...

http://www.mouser.com/Search/Product...BP7tkZuA%3d%3d

The TS3R1G or TS3R2G as shown on the data sheet seem good.

You might try asking Mr Cullins how much current can be switched on the relay lines. That would be a non-destructive way to get the drive current capability. It's not impossible that the BOB can drive 160mA into the relay but I would be pretty surprised. The reason that the torch height controller can drive a mechanical relay is that it probably has a transistor that is controlled by the signal from the BOB and is handling the relay current.

If you wind up driving a mechanical relay from the board, you will need a diode across the relay coil to prevent the coil turn-off spike from blowing up the driver on the board (think ignition coil).

The relay TS3R1G or TS3R2G looks like it will work based on your description of the voltage and current on the torch switch. Is there any AC voltage meaured across the contacts? I think that the BOB should be able to drive it as well.

Bob