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Old 19th February 2011, 10:31 AM   #1
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Question Electronic choke

What about this electronic choke for valve:

SELF DE FILTRAGE ELECTRONIQUE A MONTEE PROGRESSIVE - eBay.ch (endet 19.03.11 17:38:18 MEZ)

Cost only 2500 + shipping
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Old 19th February 2011, 10:42 AM   #2
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Looks like a regular pass regulator. Can be built for less than half the cost if you do it yourself; there's lots of schematics out there. If you're looking for an easy solution and don't want to get your hands dirty, this seems like a good solution. It'll dissipate a bit more power than a choke though.
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Old 19th February 2011, 10:42 AM   #3
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Looking at the image of the device, I think it's a transistor based voltage regulator.

Example Transistor Circuits

Constant voltage output with very good ripple rejection (as long as the input caps are large enough and the output voltage is below the ripple voltage). Simple enough to P2P or even make on stripboard. Cost of parts not more than 5 Euros. Have made many of these and use them in my circuits. Make sure the transistor can take the voltages used. I use the IRF740 or IRF840 for high voltage applications.

(edit: Looks like Mastodon beat me to it)
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Old 19th February 2011, 01:21 PM   #4
tinitus is offline tinitus  Europe
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electronic choke

if working like a choke, it should only smooth ripple, and not be a voltage regulator, yes ?

some around here are playing with a JLH ripple killer
but probably low voltage

seems it has a voltage drop of 15V, but no voltage regulation as such
and also a softstart function
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Old 19th February 2011, 01:24 PM   #5
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Quote:
Originally Posted by tinitus View Post
electronic choke

if working like a choke, it should only kill ripple, and not regulate voltage, yes ?
Yes don't regulate only drops max. 15V Vin-Vout
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Old 19th February 2011, 01:34 PM   #6
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This a reliable guy. I have bought other circuits from him and the are very good.
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Old 19th February 2011, 03:19 PM   #7
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As far as I can see, if this circuit does not offer any voltage regulation, then this seems to be an even simpler circuit than the voltage regulator, the zener being replaced by another resistor. This then works as a voltage divider, probably calculated to drop a certain percentage of volts from the gate/base of the pass transistor. The voltage drop is probably enough to "chop" off the ripple voltage of about 8-10 volts.

I have also made this circuit too. Works very well.

As mastodon puts it, if you wish to have an easy life, then just buy it. It works. No doubt about it.

Last edited by quikie22; 19th February 2011 at 03:24 PM.
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Old 19th February 2011, 03:30 PM   #8
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Could you post the schematic?
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Old 19th February 2011, 03:44 PM   #9
db! is offline db!  Canada
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Possibly a gyrator?
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Old 19th February 2011, 04:17 PM   #10
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Basically based on this,

http://www.satcure-focus.com/tutor/images/regulat.gif

replace the ZD1 with R2. Voltage drop can be calculated by Vin(R1/R1+R2). Calculate for a drop of 12-20V if you are using 400V. A good initial value to try would be R1=30K, R2=680k. You can also place a large value capacitor in parallel with R2 to improve ripple rejection, and also for slow start.

Q1 you can use irf840. All the precautions of using a Mosfet apply, ie reverse biased zener between G-S, reverse biased diode at S-D.

Alternatively, you can use this circuit concept of a capacitance multiplier.

Capacitance multiplier - Wikipedia, the free encyclopedia

Capacitance Multiplier Power Supply Filter
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