Simple power supply

Dr. Duncan Clark duncan at
Thu Sep 11 02:54:00 EST 1997

In article <5v74tp$qdi at>, kang at writes
>Dear colleagues;
>I recently developed new power supply which is totaly different from the convent
>ional one in that it does not use the core and coil and condenser for transformi
>ng AC to DC. Instead I used bridge diode just to change the AC to directional pu
>lse current. You can imagine this simple sappartus as a power supply used for pu
>lse field electrophoresis. I really hope many biologists use this idea for simpl
>e agarose gel electrophoresis.
>Following is the characteristics of the apparatus;
>       1) Cheap; you need only several dollars to make it
>       2) Simple; no trouble forever (?)
>       3) No variable volage settings; has only 2 voltage settings, 100 and 50V
>       4) It is not DC; it is pulse or pseudo DC
>       5) Maximum current is 1.5A; means you can run 15 small gels at a time
>       6) I could get sharper DNA band with this than with several hundred    
>dollar a
>       7) and many more
>I made the beta version of this apparatus and wanat to sell with 40 dollars.

This would be 'illegal' in the UK/EEC due to lack of safety and would
not be allowed to be sold. If one of the rectifiers fails short circuit
you can get full mains AC on the output with lethal consequences.  With
no current limiting this would kill. Given that a transformer and
condenser are literally only a few dollars surely it makes sense to use
that route?


The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Duncan Clark
DNAmp Ltd.
TEl/FAX 01252376288

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