high turns ratio smd transformer?

Does anyone know of a source of SMD transformer to be used to transform a
low voltage (less than 3V) input to about 125 - 150V output? I'd like
something in the range of 1:70 to 1:100 turns ratio. I can control the
amplitude of the input. Google searches have been fruitless after several
days of searching.
The secondary needs less than about 20uA. I'm trying to keep overall system
low, also.
Any ideas of vendors to search would be appreciated. I've tried
Sprague-Goodman, Coilcraft, etc., but no one seems to have anything in this
high turns ratio.
Thanks.
Dave
Reply to
starfire
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Sorry, I don't have the time to go looking for you this morning - but have you considered using two transformers (secy of first connected to primary of second), instead of one?
OK, it isn't usually as efficient as a single transformer but can actually require considerably less space (volume as well as pec area) and be a lot cheaper and lighter.
Reply to
Palindr☻me
could you use a current transformer backwards? the turns ratios are in the range you suggest. sammmm
Reply to
SAMMMMM
Sorry, I don't know what "SMD" means and you didn't state the frequency of interest, but it sounds like your app is very low power. Have you investigated vacuum tube audio transformers? They usually match impedences from 5-10kOhms to 4-8 Ohm speaker impedances. One company
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may have what you need. Check
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as a source. Your reqmts don't sound too tough. Robert
starfire wrote:
Reply to
Linda C. Werner
Surface Mount Device.
Reply to
Michael A. Terrell
Thanks for the reply.
I have considered using two transformers connected as you say. That would be a workable solution with existing devices I am aware of. Sprague-Goodman makes the GLSG family devices, one of which is a 1:17 turns ratio. I could even use two different turns ratios and match closer to the desired total ratio. I will probably go that route if I can't find a single transformer solution.
I would really like to reduce the footprint, though, as this is for a very small surface mount device (SMD) application.
Thanks again for your input.
Dave
Reply to
starfire
Thanks for your suggestion.
As a matter of fact, I'm experimenting with such a device right now. I've obtained two samples of a 1:50 turns ratio transformer from Flux. Unfortunately, the primary (going from 1 to 50) is effectively a single turn, which means very high current in the primary side, unless I use a limiting resistor in line. I'm trying to drive this from a very low current oscillator and keep the overall system current low (portable application).
When I inserted a limiting resistor inline with the transformer primary, the effective voltage across the transformer primary is decreased and I only see smaller secondary voltage. The secondary voltage is larger than the power supply voltage, though, so I think this is going the right direction. The limiting resistor keeps the overall system current down, also. I'll continue some more experiments with this transformer, though. As you say, the turns ratio is in the range I was hoping for.
Thanks for your suggestion.
Dave
Reply to
starfire
Thanks for your suggestion.
I will check the sources you've listed for such a device. I think an audio transformer with the correct impedance matching (effectively, turns ratio) and a large enough primary impedance would be a good solution. I should be able to drive it through my oscillator source (enabling a FET switch) and keep the overall current usage low.
Thanks again.
Dave
Reply to
starfire

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