Puzzling Pulse Transformer output
Puzzling Pulse Transformer output
(OP)
Hi,
I am pulsing a 1:1 pulse transformer with a 600 ns pulse and when I send 3 consecutive '1' the pulses on the output satrt to get smaller (about 350 ns). If I send 2 consecutive '1' the pulses on the output are fine. I tried putting a 1N4001 diode across the primary and secondary sides of the transformer and it didn't help. Can anyone offer any help??
Thanks,
swb1
I am pulsing a 1:1 pulse transformer with a 600 ns pulse and when I send 3 consecutive '1' the pulses on the output satrt to get smaller (about 350 ns). If I send 2 consecutive '1' the pulses on the output are fine. I tried putting a 1N4001 diode across the primary and secondary sides of the transformer and it didn't help. Can anyone offer any help??
Thanks,
swb1





RE: Puzzling Pulse Transformer output
RE: Puzzling Pulse Transformer output
Thanks,
swb1
RE: Puzzling Pulse Transformer output
RE: Puzzling Pulse Transformer output
swb1
RE: Puzzling Pulse Transformer output
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Puzzling Pulse Transformer output
Looking at the datasheet, the primary inductance is 200uHenry which i feel is high for operating at 600nSec i.e 1.3MHz frequency.....Adversly speaking, the FET that u;r driving , may not be switching exactly 0-5 V. The Diodes 1N4001 used are good only upto few hundered Hz and would infact distort your signal if used in even KHz range. I would start debugging 1st by using
1) Use BAS16 or equivalent High speed Schottky diode
for achieving free wheeling at 1.3MHz across
transformer terminals instead of 1N4001 rectifier
diode.
If the above doesn't work...
2) Use High speed MOSFETs like IRF640 or so which has very low "ON resistance" less than 0.5Ohm and has atleast 3MHz switching capability
If this also doesn't work....
3) Last, i would suspect the transformer. If it has Iron core, use transformer that has Ferrite core. Also check the primary and secondary inductance they should be as low as possible of the order of 10's of microhenries...
R u using this transfomer for a specific reason??? Why not use a better Opto isolator??? Will solve all yr issues...Let us know what come out of this....thanks
RE: Puzzling Pulse Transformer output
swb1
RE: Puzzling Pulse Transformer output
Regarding the pulse shape: It is what magnetic cores do when you do not give them a DC-free input signal. A free-wheeling diode does not restore zero flux and will not help. Use a DC blocking capacitor in series with the primary to avoid DC saturation. And make sure that the transformer is designed for your intended use. There are specs like uVs and risetime and so forth that must be met in order to get good results.
Gunnar Englund
www.gke.org
RE: Puzzling Pulse Transformer output
RE: Puzzling Pulse Transformer output
swb1
RE: Puzzling Pulse Transformer output
http://www.nve.com/Downloads/il710t.pdf
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Puzzling Pulse Transformer output
swb1
RE: Puzzling Pulse Transformer output
It is very easy, takes less time, then reading the faq.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Puzzling Pulse Transformer output
swb1
RE: Puzzling Pulse Transformer output
RE: Puzzling Pulse Transformer output
Your computer keyboard should have "Prt Sc" (print screen) key....Open Photo editor . Open your schematic page, click on "Prt Sc" key and then open Photo editor and from Edit manu, click on "paste as new image"....you should get the .jpg of your schematic at saved location....
RE: Puzzling Pulse Transformer output
Oh yes. It will work. But you have to size the capacitor accordingly. Not just pick one from the drawer.
Gunnar Englund
www.gke.org
RE: Puzzling Pulse Transformer output
RE: Puzzling Pulse Transformer output
RE: Puzzling Pulse Transformer output
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Puzzling Pulse Transformer output
RE: Puzzling Pulse Transformer output
swb1
RE: Puzzling Pulse Transformer output
RE: Puzzling Pulse Transformer output
thanks,
swb1
RE: Puzzling Pulse Transformer output
RE: Puzzling Pulse Transformer output
When you pulse the transformer you create a magnetic field which is basically storing some of the enery (charge the inductor). To get rid of the stored magnetic energy you have to "move" it somewhere else (discharge the inductor). Using a snubber circuit with a decent voltage drop will quickly change this energy into heat. Our zener/diode circuit has a little more voltage drop than the DC pulse does to allow a 50% duty cycle.
I hope that makes sense.