[ARC5] Dynamotor Experiments II

[Robert Eleazer]

This morning I installed new caps in the unmodified 21 VDC dynamotor and found that it ran fine, providing rated voltage or perhaps a bit more all the way up to 21 VDC input (295 VDC rather than the rated 260 VDC).  There was no decay of the performance with time when operated at 12 VDC, unlike yesterday, but the 45 VAC component on the output as shown on a DVOM was still there.  With 12VDC on the input it put out 161 VDC while drawing a bit under 400ma on 12 VDC.  With a 20,000 ohm load the voltage dropped to about 154 VDC.  This dynamotor has some sparking visible at one of the brushes, although the commutator does not look to be very badly worn

For the one I modified with parallel field coils, input at 12 VDC drew about 800MA.  Output was 161 VDC under no load, and 157 V with a 20,000 ohm load. The 4 VAC on the output was still there; I suppose I ought to hook it up to an Oscope to be sure.  So putting the field coils in parallel cut the output voltage drop under load in half but doubled the input current.  I just ordered a couple of 25W 1000 ohm resistors to use as a load bank.  If I take one 1000 ohm and one of the 220 ohm 25W resistors I have in series that should load the dynamotor for its full current rating with a 12 VDC input; we will see what the output voltage drop is then. 

Keep'em Sparking!

Wayne
WB5WSV


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