Driving and controlling 12, 12v dc pneumatic solenoid valves

Using Arduino Project Guidance
1

Hi! I am begging a project wherein I need to drive and control 12, 12v dc pneumatic solenoids, Im running two of the following:

My first instinct was the transistor route using a series of tip-120s with diodes for kickback and whatnot. That seemed messy so I attempted to use the infamous sainsmart 16 channel relay board:
https://www.amazon.com/dp/B0057OC66U?psc=1&ref=ppx_yo2ov_dt_b_product_details

Im no electrical engineer so pardon my ignorance. but for some reason I could not get the relay board to work, my assumption was it is not providing the necessary output voltage/amperage.

so my next attempt will use two ULN2803: 8 Channel Darlington Driver (Solenoid/Unipolar Stepper) chips:

with a circuit not much unlike this using an arduino mega for control. (I would run power from an external power supply)
62Pihw2

Will this method work to drive all 12 solenoids? Should the relay board work for this? and what power supply would be optimal? currently I have a 12v 1.5a dc and a 12v 6a dc power supply available.

2

What is the current draw of each solenoid.
If you don't know, then measure coil resistance.

That 500mA rating of the ULN chip is for a single coil.
That drops to less than 100mA for eight.
Leo..

3

  • Do not use Vin to provide load power.

  • Make sure the number of energized solenoids does don’t exceed the chip’s capability.

4

Roughly current draw if calculated by watt/volt would be roughly .42A. So if I had two of these chips power 6 coils each would that suffice?

5
  • As requested, what is the resistance of one coil ?
6

from what can gather about .42A

7

  • We measure resistance in ohms.

  • If you have a DMM (digital multimeter) use it to measure the coil’s resistance.

For example your coil resistance might be 28 ohms.

8

it is 28 ohms

9

The chip will dissipate 1.5watt with three solenoids active, which pushes the chip's temp over the 125 degrees C limit. Three chips (four ULN outputs in parallel per coil) would be a lot safer.

Six logic level mosfets on a piece of strip board seems a lot easier.
Or boards like this.
Leo..

1 Like
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3V210-08 datasheet;

3V210-08.pdf (1.5 MB)

12V 3W .... 3/12 = 250mA

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  • As mentioned above, when 3 solenoids are drive by parallel drivers, run a test to see how warm/hot an IC gets. Then try a 2 parallel test.
12

That relay board should be dead simple to drive - assuming it has enough power supplied to it to run the relay coils - and sounds to me like the best solution of all presented here so far.

You'll still need the flyback diodes to protect your relay contacts. They don't really like big sparks.

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