When you don't ground the center of a balanced supply (two
batteries in series + and -) you don't supply a ground, and the
overall voltage doesn't balance unless the current draw is exactly
balanced, so the circuit sees, say, rather than +13 and -13; maybe
+15 and -11.? There's also the problem that the impedance of each
supply (supposed to be low) depends on the rest of the circuitry
(like the +13 being influenced by the -13 and vice versa.).? No
guarantees what happened (electrically), but oscillations are not
at all surprising.
Harvey
On 4/1/2020 10:02 PM, stan_katz via
groups.io wrote:
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Hope this thread is not totally dead. The 3x switch strange
behavior with oscillations at TP1 of A4 happened to me. I have two
13.2v hand tool nicads to power my 419.? I had wired in the +13
and -13 battery leads into the instrument,? I failed to connect
the neutral wire between the batteries into the instrument power
ground (eg. the case). With that wire added, the 3x insane
behavior was gone.??
