Maker Pro
Maker Pro

Regulating voltage made it worse???

Hyteck9

Feb 14, 2020
3
Joined
Feb 14, 2020
Messages
3
Hello,

I have a curious little project issue.
I have a bluetooth board with relays on it.
The hi power contacts on the relays do not get power from the board.
For simplicity, I wired the hi power relay points to the same power src. It worked fine at first. About every 20th time a command was sent to the board, it would NOT fire the relay, even though the LED indicated the board recieved the instruction to do so for that specific relay. I would have to reboot it.
I figured the draw from the relays ( which trigger solenoids.. a big draw ) was spiking the board somehow, so I introduced a resistor and zener diode regulator to keep things calm. The meter says it is working and voltage is good, but now firing a relay just once induces the problem. I have to turn it all off and back on before a relay will fire again. The relay power is being tapped at the same source, but upstream of the resistor and diode. That is it really, the only other wires go to a power toggle switch. Why does regulating voltage make it worse?
 

davenn

Moderator
Sep 5, 2009
14,304
Joined
Sep 5, 2009
Messages
14,304
Why does regulating voltage make it worse?

It wont unless you are doing something wrong

Please show a schematic for your circuit ... else we are all just guessing
 

73's de Edd

Aug 21, 2015
3,658
Joined
Aug 21, 2015
Messages
3,658
Sir Hyteck9 . . . . .

Now, before you have to goes out and spends enny of yer hard earned munneys . . . . .

Try the addition of the two transient spike supresser diodes, now shown.
Standard practice on the relay coil . . . . . . and your inductive value of solenoid may just be creating a multi hundred volt back EMF spike across the relay contacts JUST after they have opened 1/1000 ths of an inch . . . and it arcs across that gap into the supply line.
Also consider a 100-1000 ufd electrolytic across the YELLOW X junction to ground . . . . to be sure that the controller module receives a stable voltage.

RE- REFERENCING . . . . .
upload_2020-2-14_3-41-52.png


73's de Edd . . . . .

If you can think of a color that does not exist, is it being a pigment of your imagination?


.
 

Hyteck9

Feb 14, 2020
3
Joined
Feb 14, 2020
Messages
3
Hello!! I have tried these and many other potential fixes this morning. No luck with those, but I think I did figure out the problem. When the solenoid fires, it seems to be disrupting the bluetooth radio reception. If I place the solenoid a tennis ball's distance from the controller, it fires repeatedly and consistantly. This sucks, because who wants a circuit footprint that big! Ha! So, how to shield the controller from the solenoid, without blocking the bluetooth radio reception at the same time!?!?
 

bertus

Moderator
Nov 8, 2019
3,393
Joined
Nov 8, 2019
Messages
3,393
Hello,

What shape is the solinoid?
Perhaps a shielding around the solinoid might help.

Bertus
 

Tha fios agaibh

Aug 11, 2014
2,253
Joined
Aug 11, 2014
Messages
2,253
I'm surprised it works at all with that zener regulator. The controller is limited to 15ma through the 300Ω resistor and most relays draw at least twice that.

I would employ all the good suggestions given. Use a better more efficient regulator (lm7812 or switching type), use flyback diodes to mitigate spikes, add electrolytic cap to stabilize voltage and try shielding (nickel copper fabric or even a sheet of thin metal insulated with plastic).
 

TomGeorge

Sep 7, 2013
3
Joined
Sep 7, 2013
Messages
3
Hi,
Questions that should have been asked at the start of this tread.
What are the specs of the solenoid?
What are the specs of the relay?
Have you got the solenoid wiring AWAY from the wiring to the Bluetooth?
Make your power connections a star formation from the power supply, do not daisy chain your power supply wiring.
What is your power supply? (specs)
Sorry but for a decent thought out solution we need information about your project.
Tom...
 
Top