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Topic: It works!! Even when others said it wouldn't. (Read 3075 times) previous topic - next topic

Grumpy_Mike

Just think if this circuit did work it would be the ultimate in low drop out regulators. That is you can regulate right down to zero volts drop across the regulators.
I wonder why no one has done that before ... hum .....  :~

sdturner

Less attitude and more facts would be appreciated. If it works we will all be enlightened with no need to gloat. If not there will be less embarrassment.

My experience tells me that you are seeing leakage current through the regulators, but a few milli-amps of load will cause the negative voltage to disappear, however, if I am wrong I would really like to know. I will have to go back to the old reference books and review the internal design of linear regulators.

Eriba

#17
May 10, 2012, 07:13 pm Last Edit: May 10, 2012, 07:40 pm by Eriba Reason: 1
I must admit that it does appear to work - but only because the regulators happen to be half voltage of the 18V supply. Well, apart from the fact that both outputs surely must be +ve

The 7809 is regulating correctly, producing 9V - the remaining 9v are dropped across the (incorrectly configured) 7909.

If the supply voltage was for instance 24V, the outputs would be 9V and 15V.


John

"Everything should be made as simple as possible, but no simpler."

florinc

Did you buy 2 extra meters just for this experiment?

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