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Need a bi-directional dummy load, electronic or passive for control boxes controlling DC actuator motors to test output voltage and current when an actuator motor is not available. Preferably under different current conditions, that is, the dummy load, would create a load to force the port on the control box to increase or decrease the current output so as to simulate a real load and, preferably, powered by the output port of the control box under test.

Looking for a dummy load to cover 10Vdc to 50Vdc with currents up to 7 Amps.

Just as in the real situation, the direction on the dc motor, and therefore, the extension of retraction of the shaft, is controlled by polarity reversal from the hand-piece while the wire position remains the same. Some control boxes use direct dc, others use pulsating dc current control.

One of the problems with electronic dummy loads is simulating polarity or voltage reversal without changing the power wires around.

Any ideas or projects already built of this type you have come across.

 

 

 

 

 

 

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  • 2 weeks later...

.....so far, lots of views, however, no replies.  It appears, there are many members interested in this project.

So, lets start with the basics. A control box running actuator motor(s) has wide applications.  The control box, usually, outputs a DC voltage to its ports, when a button on the handset is pressed,  and the rotation of the motor depends on the direction of current. The simplest connection between an actuator motor and the control box is a mono phone type connector.

There are quite a few circuits on the net, just google "dummy load circuit" or  "dummy load" under images. Most of these employ a Darlington pair in their final stage. Here is a URL:  https://www.google.com.au/search?q=dummy+load+circuit&client=firefox-a&rls=org.mozilla:en-US:official&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjzn5S_w-PKAhWmGaYKHdH5B_QQ_AUIBygB&biw=1280&bih=656#imgrc=_

The output voltage from the control box can be thought as a pulsed DC of variable duration. However, most of the circuits, in the above url, impose a restriction because the final stage is not bi-directional. One way of overcoming this limitation is a to use a full-wave bridge rectifier,  to turn the "negative pulse" into "positive pulse"

...... more to follow

 

 

 

Edited by Projects Make You Think
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