24V LED with PWM for pump

Hardware
1

Hi!

I am currently working on a HERMS setup and when doing some testing, I found out that the pumps from BrewPi are really, really quiet. This is ofcourse great, but twice I forgot they were still running while disconnecting hoses.

In order to give me a visual reminder the pumps are running, I want to add LED’s on my conrol panel. The LED’s I like however, are 24V LED’s. In an other thread on this forum, Elco suggested to use DC-DC SSR’s to solve this issue.

My electronics knowledge is a bit rusty (and I am an amature), so I would like to ask if somebody would be so nice to confirm my connections are correct.

pump_control
pump_control1180×497 17.4 KB

What you see:
5V transformer to feed the BrewPi
24V transformer to feed the pumps

The BrewPi sends a PWM signal to a manual switch (to disconnect without having to reach to the laptop in case of forgetting to turn something off) that goes to the + input of the SSR. The - input of the SSR is then linked to the Pump to deliver the PWM signal (so the PWM signal goes through the SSR). On the other side of the SSR, the 24V + is switched and in this way, the LED is switched.

The pump ofcourse gets a +24V and a ground from the 24 transformer, as well as a ground from the BrewPi to sync the relative grounds.

Really hope somebody can tell me what I have done wrong (or that this is correct :stuck_out_tongue: ) Thanks in advance!

2

It looks plausible to me, but this is really something @Elco will have to look at.

3

That would be awsome if Elco can have a look.

This is option 2:

pump_control_option2
pump_control_option21422×671 27.1 KB

But I am in doubt if this works because I don’t know the internal resistance of the SSR. Think when this is too low, there won’t be enough current left to give good signals to the pump since all the current flows then through the ssr and not towards the pump (path of least resistance).

4

You can put the SSRs control signal in parallel with the pump control signal like your second drawing.