# Identification of DC Connector

#### chrobry

Joined Jul 20, 2021
2
I have a paddlewheel flow meter that looks to be a solid block of plastic (polyoxymethylene) with no access to the electronics and no apparent seams. The power supply is 3.8-24 VDC, 50mA max. The output signal is a 0-120 Hz wave pulse train with a signal amplitude equal to the supply voltage. It has a type of connector in which the DC power and signal pass through the wall of the housing without any conductor contact. The clamp holds the connector in a specific orientation. The connector is 1/8" wide. See photos.

This flow meter was a custom build by Malema Engineering Corp.

It does work. Although I am unable test the pulse train, the signal is 12 VDC corresponding with my 12 VDC power supply and the voltage does fluctuate when I spin the paddlewheel by blowing through the meter.

Does anyone know what type a connector this is? I can't find anything like it.

Also, has anyone seen this type of design with the electronics contained in a plastic block?

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#### Yaakov

Joined Jan 27, 2019
4,007
That's not a connector, it's a Hell Effect transistor. Try putting a strong(ssh) magnet over the place where it mounts and rotate the wheel.

Don't go nuts with the magnet, you don't want to diminish the internal one.

#### chrobry

Joined Jul 20, 2021
2
Thanks Yaakov. Now it all makes sense. Quite the simple flow meter. As you can tell, I'm not a EE. Is there a simple way to convert the pulse train signal to a 4-20 mA signal?

Last edited:

#### Yaakov

Joined Jan 27, 2019
4,007
I'd be looking for something like this: https://www.acromag.com/shop/signal...y-pulse-pwm-input-12-32v-dc-loop-local-power/

Just an example. You need to know the pulse frequency range. I would contact a sales engineer at a company that makes a converter and get help. Also, confirm my assertion that is a hall effect device. It seems obvious, but contact Malema and inquire about it. Their website seems very active and I expect they can help.

#### Irving

Joined Jan 30, 2016
2,422
Thanks Yaakov. Now it all makes sense. Quite the simple flow meter. As you can tell, I'm not a EE. Is there a simple way to convert the pulse train signal to a 4-20 mA signal?
Define simple? Off-the-shelf units as @Yaakov identified are simple to set up, but expensive, typically $250-$350 or more. There are chips to do this conversion and a simple frequency to 20mA loop transmitter could be built by someone with reasonable soldering skills for a lot less than \$100.