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Everything posted by congo5

  1. Getting requests for the Current Feedback Stat amp files so

    have at it


    1. Mandrake5


      Hi Congo5

      I read the thread about the Current Feedback Stat amplifier that you build and i think its really cool.

      I donwloaded the zip file you provide (thank you for sharing) and i dont seem to find an updated schematic of the board. Please can you send me the schematic file?

      I have the 2017 version of Document and Staxpcb files from Kevin Gilmore but the cfaelectrostat.pdf schematic file use small TO92 transistors....???

      Yours have KSA1156 and KSC2752.

      Have a great day.



  2. looks like I'm the one that caused trouble, not you.... those sinks above are much bigger than mine. you should be fine but do watch temps and measure across the 100r if you want to know what its running at ...
  3. so 4.5ma? I did not change it cause did not feel I needed to would think 9ma is enough not telling people what to do just what the stock values were from Kevin
  4. my board is a direct copy of Dr Gilmore's layout and values. so all credit goes to him. I saw no need to make resistor value changes. Some things can be adjusted as Michael did but with enough heat sink it works just fine as is. A stable temp is good if you want stable current through the output stage think mine were about 18ma warmed up on 400v rails I have two working amps and no plans to mess with them. Thanks
  5. Yea, good enough for me on USA ~122vac with an Antek AS=1T300 and my "as built" BH supply pick a transformer, measure its output. build your power supply and test what it needs to regulate then adjust accordingly, might not have exact output you want, doesn't matter if within 10% or so if I send my transformer and PS to Jose it might not work good enough on his line voltage you have to test and set it up or run a bit more regulation and heat to have some headroom
  6. Yes, have made boards from those gerber's and they work just fine. when I last ordered some (19-Oct-2017) it said Jan 2018
  7. for the CCS power should go through the LED to the base and also to 10k string to other side not emitter to resistor string cut trace at E and connect to base IF same as your board make like schematic.......?
  8. at one point there was an error on that board, Kevin fixed it problems were, both outputs stuck on -3V, adjusts only .1v, OP07 servos do nothing, lower LED not lit, I abandoned it and moved on to a newer version after finding this:
  9. So Glad you like it. never sure what someone else will think / hear its a good thing I did not build this first might have found an even more expensive hobby
  10. Yea OK thanks, enough amps to kill the cheep bridges I was trying to use I forget things that don't come up, but hey I'm OLD
  11. I don't know about the 25A draw not sure / don't remember inrush was above that judging by damage at times should have measured it but didn't the average magnetic 15A circuit breaker might take 80A to trip instantly I sometimes see startup amps on a 3ton A/C go over 110A on 25A fuses and 30A breakers was using 4 boards it was two years ago think 5A running on 120v circuit or about 600W at idle from the wall and that's with a low bias of 1A per board 1/4A per pair, 150mv each 0.47R emitter resistor Yes that 90% efficienct 800W P/S looks right to me for two boards. It depends on your speakers, 8ohms? 4ohoms? how much power they and you require. How much Bias / class A power you plan on if balanced each board only sees half the load so an 8R becomes 4R when calculating Class A or power supply needs
  12. There are resistors that fit better but I saved a lot of money by getting 100 Xicon's Yes its a very tight fit That SMPS looks interesting to me and its current limited to 1050W, would add the fan for sure. I would like to try it, with two 50v feeding the unreg and with the GRLV set to 40v or slightly lower if using balanced as I don't really need 640 Watts RMS class AB been wanting to take mine apart and make it into mono blocks that could be used as stereo or balanced and so it wouldn't weigh 80LBS also need to double the size of heatsinks or add water cooling And Yes I had trouble on startup with 1000va of transformer feeding close to 200,000uf of caps the current inrush blew 12 35A diode bridges and the resulting short to ground blew up many of my soft start components
  13. yes but you =SuperStar first links no=go second work, Thanks
  14. The amp camp was meant to be an easy to build and safe introduction into the hobby. I have six Amp Camp stereo amps so as an intro it worked quite well All are used for phones, they will drive Fostex T50's loud enough to quickly damage your hearing. None of my off the shelf 89db/W speakers work well with this amount of power. not that it sounds bad just not enough drive to wake them up. the F5 does do the job. you might like them, you might listen differently think small room, efficient speakers, modest volume DiyAudio sells quality kits and have excellent documentation +1 what Craig & JimL said
  15. The problem with mounting the 10m90s for CCS 580v bias is that there is a lot of voltage on that metal tab I have not measured it but it has to be well over 600v the heatsink is 6/32 mount hole most times the transistor hole is too small for any PPS washer I have to fit they will crack if you force it and the PPS washers require a M3 or 4/40, so no 6/32 screw good news is there is not a lot of heat here as its putting out ~1.5ma so I have used a nylon 6/32 with 2mm oxide pad and thermal grease Peek would be better have also reamed out transistor hole before mounting to fit washers and 4/40 SS screw with nut through heat sink hole this is all covered in one of the older threads but they are large 600v when let loose is exciting and yes I have had flaming boards this is what I get away with YMMV
  16. In the Blueman2 picture above it looks to me like a metal screw in the 10m90 for the headphone bias CCS And if so, do they make PPS washers that are white? It looks good but for that one concern thanks
  17. The THAT340 is a sub for jfets, because they are hard to find and costly I changed mine because offset would move 100mv over the range of pot. in hindsight might be just wiring, or solvable with a couple resistors to ground. that pot /bjt input interaction could also cause noise sounds very good both ways
  18. What bias are you running? I turned mine down by stacking another resistor IIRC and have sinks glued to the top of transistors There is lots of copper on Kerry's board but a limited amount of surface area to dissipate heat. mine runs cooler in the case if I turn it on its side so air can rise vertically along the board surface. But yes ..............in a tiny case it runs hot. (from notes on ssdynalo mini) 255R bias +1.8k =223R avg .280mv/20R=14ma .28W
  19. well then my Jfets are exactly backwards for K170 J74 but those are K246 J103 so OK (if it matters) they did work fine here but not so in Dynahi, used K170 J74 the silk is marked so Emitter – (E) >> Source – (S) Base – (B) >> Gate – (G) Collector – (C) >> Drain – (D)
  20. I saved that pic but can't find it here is my SSDynalo with jfets N channel on top P channel on bottom
  21. Looks to me like these could sub for input transistors. PBHV2160ZX And PBHV3160ZX data sheet is very much same except for lower collector and emitter capacitance Yes/No?
  22. at bottom center of each side are two holes for a solder loop or I plan to use spade connectors that is where Kevin put them and I copied his work Another benefit for the different caps are that they are shorter. So the board assembly is smaller
  23. Yes I consider artistic ground planes "Fancy" This amp seems to have very good noise rejection as I can't hear anything. but why not have a ground plane...... This is what I will make next, when the parts come in Think this is better then my last, with ground plane, lower ESR and a bit smaller.
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