dsavitsk Posted July 19, 2015 Report Posted July 19, 2015 the noise spikes are 120hz (100hz for you) and due completely to the switching noise of the input diodes. every power supply, even tube rectified ones do this. The idea is to remove the spike noise, and its not easy. caps across the diodes, etc, just does not work. Nice design, Kevin. Any thought to changing the first cap to a pi filter?
Pars Posted July 19, 2015 Report Posted July 19, 2015 the noise spikes are 120hz (100hz for you) and due completely to the switching noise of the input diodes. every power supply, even tube rectified ones do this. The idea is to remove the spike noise, and its not easy. caps across the diodes, etc, just does not work. Would changing to discrete input diodes, perhaps even Schottkys (31DQ10?) help for this?
sorenb Posted July 19, 2015 Report Posted July 19, 2015 Nice design, Kevin. Any thought to changing the first cap to a pi filter? isn't at pi filter there to reduce ripple? if the caps doesn't ground the spikes why should the coil resist those?
kevin gilmore Posted July 19, 2015 Author Report Posted July 19, 2015 (edited) everyone wanted tiny. they got tiny. i could do singles sic diodes or schottky dioes, board has to get a bit bigger. and the noise is already 140+ db down. i can't measure that at home, my led lights over the bench generate 7mv into a single turn of wire. and the switcher in the burglar alarm, and the high frequency switcher in the whole house UPS... and the switcher in the variable frequency drive for the AC... and at work, just barely can i measure. the stuff that does -160 to -170db seems few and far between. And in the stupid price category. Edited July 19, 2015 by kevin gilmore
JimL Posted July 19, 2015 Report Posted July 19, 2015 (edited) kevin gilmore on 19 Jul 2015 said: "...by the way, so far, I can't even get close to these numbers with a shunt regulated supply, the noise rips right thru the main current source." I wonder if using a cascode current source would help? Just a thought. Edited July 19, 2015 by JimL
kevin gilmore Posted July 19, 2015 Author Report Posted July 19, 2015 cascode current sources at 1 amp, not so easy parts are not available
luvdunhill Posted July 20, 2015 Report Posted July 20, 2015 the noise spikes are 120hz (100hz for you) and due completely to the switching noise of the input diodes. every power supply, even tube rectified ones do this. The idea is to remove the spike noise, and its not easy. caps across the diodes, etc, just does not work. I find a C || R+C across the secondary and a common-mode choke after the first cap seems to be about as good as you can do. The filter needs to be tuned to the transformer though.
PretentiousFood Posted July 20, 2015 Report Posted July 20, 2015 cascode current sources at 1 amp, not so easy parts are not available Not with depletion mode parts, but with enhancement mode devices it works quite well. Here's something I'm using for a phono supply at 200mA or so, but it works well at higher currents with a different biasing scheme. You could use a mosfet cascode CCS (like Gary Pimm's) and feedback to the shunt device for better noise rejection, too.
Helium Posted July 24, 2015 Report Posted July 24, 2015 Kevin, is this thread all devoted to goldenreference4.zip? What about goldenreference and goldenreference3? Is goldenreference4 direct replacement for those? And you opted to get rid of TO-3 transistors?
kevin gilmore Posted July 24, 2015 Author Report Posted July 24, 2015 all are the same design, the first one has on board to3 transistors. you can always use the goldenreference4 and mount the to3 transistors on an external heatsink.
mwl168 Posted August 25, 2015 Report Posted August 25, 2015 (edited) On 7/16/2015 at 7:17 PM, kevin gilmore said: its a 10 volt reference, the feedback resistors are 1.5k which is a divide by 2. So if you change the top 1.5k resistor you can get any voltage you want. 750 ohms makes it 15v http://gilmore.chem.northwestern.edu/goldenreference.pdf change R8,R9 For my own benefit and possibly others, can someone confirm or correct the following: The regulated output voltage is: for V+: ((R8 + R7) / R7) x 10 (reference voltage of D5 - LT1021-10) for V-: ((R9 + R10) / R10) x 10 (reference voltage of D7 - LT1021-10) On the goldenreference4 board silkscreen, R7, R8, R9 R10 are all 1.5K. R7 and R8 are connected and R9 and R10 are connected. R8 and R9 are the 1.5K resistors closer to the DN2540 on each side of the board. Thanks! Edited February 7, 2017 by mwl168 1
kevin gilmore Posted August 25, 2015 Author Report Posted August 25, 2015 yep that is the ideaover the weekend i replaced the 1.5k resistors with 2k original vishay resistors rated at .01% and 5 ppmvoltages much more accurate.version 5 of the goldenreference board has a place for 1M pots that go in parallel with these resistors forthose that just absolutely need to adjust to 6 places(actually those pots may influence overall thermal stability, cermet pots required) 1
Pars Posted August 25, 2015 Report Posted August 25, 2015 (edited) On 7/19/2015 at 3:10 PM, kevin gilmore said: everyone wanted tiny. they got tiny. i could do singles sic diodes or schottky dioes, board has to get a bit bigger. For the Gilmore dynamic V2 I built (on Justin's PCB), I did some adapter boards and used 31DQ10 Shottky diodes in place of the monolithic bridges (which I think are the same bridges used here). These use a Mill-Max 90 degree pin and plug right into the monolithic bridge footprint. I would think these could be adapted to most any discrete rectifier diode assuming the room was there to accommodate them. Edited February 27, 2018 by Pars 3
b0bb Posted August 26, 2015 Report Posted August 26, 2015 Parts connexion sells them.http://www.partsconnexion.com/kits_sub_assemblies.html
insanity Posted August 29, 2015 Report Posted August 29, 2015 I have a few questions concerning the capacitors on the GR LV board, if someone is kind enough to answer1. What are the recommended voltages of the tantalum caps on the GR LV? Is it the same for the 10uf and 47uf?2. Whats the voltage rating for the 47pf disc cap?3. Is this the correct 4.7uf 63v cap? http://www.mouser.ch/ProductDetail/WIMA/MKS2C044701M00JSSD/?qs=ISKKXg98%2b1mdri3wReBbVQ%3d%3d4. Are these the correct 0.01uf caps? http://www.mouser.ch/ProductDetail/WIMA/MKS2C021001A00JI00/?qs=%2fha2pyFaduj8D%2b74lAuj%2fVfU0ISRQQyVkMGVwoGjK1pT08hCW9OSJ62gFby%2fdbTu Thanks for helping
kevin gilmore Posted August 29, 2015 Author Report Posted August 29, 2015 (edited) 1) 35V 581-TAP476M020CCS don't have a link for the 10uf2) does not matter I used these 810-FK28C0G1H470J3) I used these 505-MKS2-4.7/50/10 which are in stock and 50V, more than enough4) I used these 505-MKS2.01/63/10 Edited August 29, 2015 by kevin gilmore 2
Pars Posted August 29, 2015 Report Posted August 29, 2015 As far as transformer for these things, if I wanted to build one up to power a multiamp, and configured for +/- 20V output, would a 2 x 23VAC transformer be too high? Just thinking of stuff I have laying around without buying a new trafo. If I did use this, obviously there is going to be some voltage leftover to dump and this will cause some heat... anything I would need to be aware of here?
insanity Posted August 30, 2015 Report Posted August 30, 2015 1) 35V 581-TAP476M020CCS don't have a link for the 10uf2) does not matter I used these 810-FK28C0G1H470J3) I used these 505-MKS2-4.7/50/10 which are in stock and 50V, more than enough4) I used these 505-MKS2.01/63/10 Thanks Kevin.
kevin gilmore Posted August 30, 2015 Author Report Posted August 30, 2015 2 X 22 volts should be just fine, still need some heatsink on the pass transistorsdoes not seem to be a standard value though
kevin gilmore Posted September 19, 2015 Author Report Posted September 19, 2015 I have posted the goldenreference6 board, has options for center tap transformer, and dual windingsfor next time
Pars Posted September 19, 2015 Report Posted September 19, 2015 I find a C || R+C across the secondary and a common-mode choke after the first cap seems to be about as good as you can do. The filter needs to be tuned to the transformer though.I've tried this a couple of times (R+C across the secondary), but have never tried to measure it. 330 ohms and 0.022uf. See John Swenson's posts here:http://www.diyhifi.org/forums/viewtopic.php?f=15&t=1957&hilit=transformer+ringing
mwl168 Posted September 24, 2015 Report Posted September 24, 2015 Does it matter what forward voltage LED to use so long as D2/D8 and D1/D9 match?
nopants Posted September 24, 2015 Report Posted September 24, 2015 For KGSSHV duty does this even need heatsinks? How much heat is the package itself good for?
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