[Open_electroporator] Culture Shock transformer tests

John Griessen john at industromatic.com
Thu Jun 16 15:56:23 UTC 2016


Wednesday I measured wire size of a likely transformer from a laser printer.  That will help when deciding
how to have a transformer made.  A laser printer power supply is about the right volt range when a doubler is used --6 or 7kV is 
why I am modeling mine after them.  The E shaped magnetic core halves used in them are 11mm on a side.

Then I made a test circuit driven by  a lab pulse generator that could deliver 2 Volts to the primary side,
and with a snubber diode as in the sketch visible with photo named transformer_test.jpg.  When I get more parts picked out that
diode may go.  Running the test circuit showed a lower effective turns ratio than when open circuit.  The load was 30k Ohms on the 
secondary.  The ringing on the primary volts waveform may be partly instrumentation, but it can be reduced by a little capacitance 
at the 28 Volts stage.  More capacitance will be very likely since the input impedance equivalent for 30k ohm
referred to primary "as if" there were no transformer is divided by (turns ratio)**2.  So the input impedance is about 10 Ohms 
reactive.  The DC resistance of the primary is 3 Ohms.  I sent some info to my most likely China supplier, but no response yet.
They were the most responsive of several, but I may send some specs/questions to others soon also.

Today, next, I build a transistor pulser with 28VDC.  Where will the little transformer saturate?
We shall see.  Capacity of an E core to hold energy is related to volume of it for the same material.
The maker of transformers says all range of core sizes are available.  About a ten microsecond pulse
is OK for not making singing noises (frequency of the whole cycle can be above 30kHz).  I've not done this kind of test before, 
but I guess that as a pulse top goes out in time sagging at the secondary, the saturation limit will be reaches and
the slight sag will turn into a cliff drop.

John Griessen
busy busy
-------------- next part --------------
A non-text attachment was scrubbed...
Name: transformer_wire.jpg
Type: image/jpeg
Size: 72119 bytes
Desc: not available
URL: <http://cibolo.us/pipermail/open_electroporator/attachments/20160616/617377cb/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: transformer_test.jpg
Type: image/jpeg
Size: 409578 bytes
Desc: not available
URL: <http://cibolo.us/pipermail/open_electroporator/attachments/20160616/617377cb/attachment-0001.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: wire_size-sm.jpg
Type: image/jpeg
Size: 122392 bytes
Desc: not available
URL: <http://cibolo.us/pipermail/open_electroporator/attachments/20160616/617377cb/attachment-0002.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: transformer_volts-sm.jpg
Type: image/jpeg
Size: 145658 bytes
Desc: not available
URL: <http://cibolo.us/pipermail/open_electroporator/attachments/20160616/617377cb/attachment-0003.jpg>


More information about the open_electroporator mailing list