John Broskie's headphone design using pentodes - Page 2

ncc · 11th July 2009, 02:56 AM

Quote:

Originally posted by rman

I built this regulator.

http://www.glass-ware.com/tubecircuits/High_Voltage_Regulator.html Broskie regulator

It didn't work... at least I couldn't make it work.

Cheers.

I know at least one man who could make it work, see:

Here is his main site:

a very infomative site that I like very much

Cheer

rman · 11th July 2009, 04:00 AM

Hi ncc.

From the page of your second link:

Quote:

There is a 1µF capacitor connected across the load resistors, I found that with a purely resistive load the regulator will not 'power up'.

Maybe that was my problem when trying to test it!

I still have this thing laying around, should check it over and try again.

Cheers.

rman · 14th July 2009, 05:28 AM

After rechecking the board I found a missing connection after about a minute. Months ago when I built it, I couldn't find the flaw.

It regulates voltage alright. will have a look with the scope tomorrow.

ncc · 14th July 2009, 06:38 AM

Quote:

Originally posted by rman
After rechecking the board I found a missing connection after about a minute. Months ago when I built it, I couldn't find the flaw. It regulates voltage alright. will have a look with the scope tomorrow.

Hi rman,

Nice to hear that you've found the error

This regulator use a floating power supply for the reference voltage and error amplifier, I've experimented with this regulator by using a RC filter then a regulator (a LT3080) for the floating power supply, after that, high voltage output of the regulator is much cleaner than the original design.

Cheer

rman · 15th July 2009, 02:28 AM

hi ncc.

Great idea! Regulating the op amps supply makes a lot of sense to me as most op amp supplies are regulated.

Well, I had a look at the output and it is oscillating quite nicely at about 3 MHz, 0.3v pp. I put in a larger gate stopper (1k) as close to the gate as I could get. This only distorted the 3 MHz waveform.

The load for this test is a big wire wound pot set to 12.5k (20ma. @250v). It was intended for a phonostage, the regulator that is. Interestingly, when the load is adjusted to about 12.1k, the oscillation stops. The Mosfet is an IRF BC40 (found on shop floor at work). swapped in an IRF 540 and the amplitude of the oscillation rises. I really don't' know enough to account for all this. I can only conclude that layout is critical, and that mine is not great.

I guess we have hijacked this thread as the original topic seems to have disappeared.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
John Broskie Aikido boards	Original Burnedfingers	Tubes / Valves	1	12th October 2010 08:57 PM
Beam pentodes and suppressor-grid pentodes of same type	jon_010101	Tubes / Valves	3	2nd May 2009 11:18 PM
Design using EL42 output pentodes	phil_2	Tubes / Valves	61	13th November 2008 11:10 AM
John Broskie's enhanced T8	CarlyBoy	Tubes / Valves	13	8th October 2006 06:13 PM
Where is John Broskie ?	reinhard	Tubes / Valves	7	8th October 2002 01:27 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

14th July 2009, 05:28 AM	#13
rman diyAudio Member Join Date: Oct 2007	After rechecking the board I found a missing connection after about a minute. Months ago when I built it, I couldn't find the flaw. It regulates voltage alright. will have a look with the scope tomorrow.

15th July 2009, 02:28 AM	#15
rman diyAudio Member Join Date: Oct 2007	hi ncc. Great idea! Regulating the op amps supply makes a lot of sense to me as most op amp supplies are regulated. Well, I had a look at the output and it is oscillating quite nicely at about 3 MHz, 0.3v pp. I put in a larger gate stopper (1k) as close to the gate as I could get. This only distorted the 3 MHz waveform. The load for this test is a big wire wound pot set to 12.5k (20ma. @250v). It was intended for a phonostage, the regulator that is. Interestingly, when the load is adjusted to about 12.1k, the oscillation stops. The Mosfet is an IRF BC40 (found on shop floor at work). swapped in an IRF 540 and the amplitude of the oscillation rises. I really don't' know enough to account for all this. I can only conclude that layout is critical, and that mine is not great. I guess we have hijacked this thread as the original topic seems to have disappeared.