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Re: also...more L options [message #30193 is a reply to message #30188]

Fri, 21 January 2005 12:54

Damir
Messages: 1005
Registered: May 2009

Illuminati (2nd Degree)

I`d do it "right" - use 150mA choke (then - if needed - we can use the full current capacity of the PT) and power resistor (say, 12k/10W) parallel to cap to draw the critical current. What you think?

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Re: also...more L options [message #30195 is a reply to message #30190]

Fri, 21 January 2005 13:02

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

Don't forget Handmade Electronics, in PA. they *MIGHT* have better prices on some of the hammond Iron.

I get my orders from him the next day with UPS ground shippments, which is a benefit not to be ignored( not to mention he's treated me well ).
regards,
Douglas

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Re: also...more L options [message #30196 is a reply to message #30193]

Fri, 21 January 2005 13:14

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

Hey-Hey!!!,
I would rather just get adequate L. For 20 Hy and 250 volts input, this works out to about 10 mA of load. keeping the current lower will reduce radiation, which is a reasonable goal.

The IDH rectifier will allow the rest of the cathodes to get warm enough before it starts conducting so a load will be presented to the filter.

A resistor to draw an additional 4-6 mA would be useful perhaps as a safety feature. It will draw about half critical current, and keep voltage from going all the way to root2*RMS. Perhaps 25-30kOhms...
regards,
Douglas

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PSUDii say-eth... [message #30208 is a reply to message #30193]

Fri, 21 January 2005 19:27

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

Hey-Hey!!!,
On the resistor to force a critical curent load. I went in playing with PSUDii and a resistive load. 250 volts in, 20 Hy and fiddled with resistor values. I got up to 45kOhm and did not cross 300 volts on a long term basis, and figured it was plenty to keep things in check, and from behaving like a cap input supply.

V-squared over R at 300 volts shows dissipated power to be 2 watts on a 45k resistor. A 5W ought to run cool enough. 5 9k1 1/2 watt will also work if you feel like experimenting. Since B+ is ~200, continious dissipation will be less than a watt for a 45k resistor.
regards,
Douglas

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