TTL for Air Control, 18 mA Current



I'm retrofitting a Gerber Sabre 408 and it's going good (can move and home X, Y, and Z, and am mostly there with the spindle).

For the air control for the ATC there are 24v DC solenoid valves. I ordered this 8 port DC SSR SainSmart relay board from Amazon:

It ~looks~ like the input TTL draws 18 mA, which is much higher than the 5 mA the Masso G3 supports. Am I reading that correctly? Unfortunately documentation is sparse for that relay board (which isn't like SainSmart usually), so all I have to go off of are the specs listed on Amazon.

Question: If I hook one up to an output and it is too much will it just fry that one output? Or am I risking the entire G3 (or all outputs) to test this?

If this won't work I'll send it back and get these from Amazon (which are featured on the Masso documentation TTL page):



MASSO Support
Staff member
those relay boards have no documentation and are nasty, some users have damaged their controllers. If you don't have good knowledge about electronics and can't check the relay board voltages etc then it can cause issues.

we are in the process of releasing our relay boards in the next few weeks to avoid these issues.


Thanks for the reply. That's good you're coming out with relays known to work with Masso.

After doing some reading I think I'll just use some LM358 dual op amps (one per relay) I have on hand to create a voltage following buffer. The Masso will send out 5v, and the LM358 (which needs less than 1mA as a trigger at 5v) will output 5v but at a much higher potential current (more than enough for the relay boards 18mA - 25mA requirement) powered from a separate 24v input. That will at least be enough to get me up and running and be completely safe for the Masso controller. I wouldn't go this route except that I have everything on hand (op amps, circuit board, screw terminals, etc).