GeorgeP Posted April 23, 2015 Report Posted April 23, 2015 its getting pretty tight... http://gilmore.chem.northwestern.edu/kgsshvcarbon.jpg laying the rest of them horizontal is going to be a bit of trouble. For those who still have c2240 and c2705, are the newer pzta part subs better? Also, if one used the 1486 would it need to be heatsinked given your comments on the stn9360?
kevin gilmore Posted April 23, 2015 Author Report Posted April 23, 2015 no difference between the 2sc parts and the pzta or mpsw or mpsa parts 1486 does not need heatsinking. About 188mw
insanity Posted April 23, 2015 Report Posted April 23, 2015 If anyone wants to do a board run of the carbon I would be interested. I don't know who many working carbons are around at the time, but is there anyone who can comment on their strength and weakness compared to our other amps?
nopants Posted April 23, 2015 Report Posted April 23, 2015 you can get your own one-off done, won't break the bank I think JoaMat is the only one with a working unit at this point, maybe Kevin? Beta tests are open, register at http://gilmore.chem.northwestern.edu/boards/ I have a set of the boards prior to these upgrades if you're interested. I think it's equivalent to the version that Birgir posted earlier in this thread
spritzer Posted April 23, 2015 Report Posted April 23, 2015 Mine are ready for testing but other stuff has taken over for a while. Might even be pushed back further for the new Megatron PCB. As for SMD, if you want resistors that are equal to the RN60D's then they are 1$ each or even more. SMD was never designed for HV in mind...
GeorgeP Posted April 23, 2015 Report Posted April 23, 2015 no difference between the 2sc parts and the pzta or mpsw or mpsa parts 1486 does not need heatsinking. About 188mw Great, thanks. Just need to check the pin-outs on the parts - hopefully not much twisting will be needed.
JoaMat Posted April 23, 2015 Report Posted April 23, 2015 (edited) / Edited November 11, 2015 by JoaMat
UFN Posted April 23, 2015 Report Posted April 23, 2015 I have Carbon boards as well, but unlikely to have time to do anything with them for at least a couple of months. Even if they are not the newest version I assume they are OK to use? //UFN
nopants Posted April 23, 2015 Report Posted April 23, 2015 Birgir has said they're untested, so same boat as the newest version
kevin gilmore Posted April 23, 2015 Author Report Posted April 23, 2015 (edited) latest version with correct resistor values for Kerry's servo http://gilmore.chem.northwestern.edu/kgsshvcarbon.jpg parts set for 16ma at 450v Edited April 23, 2015 by kevin gilmore
JoaMat Posted April 23, 2015 Report Posted April 23, 2015 (edited) / Edited November 12, 2015 by JoaMat
kevin gilmore Posted April 23, 2015 Author Report Posted April 23, 2015 no, just 2 transistors for the servo output drive. identical to Kerry's schematic. the final output is the Motorola part because its about 350mw and if you turn the current up, its more like .5 watt
JoaMat Posted April 23, 2015 Report Posted April 23, 2015 (edited) Thanks, it's great to have Kerry's Servo on board. Edited November 12, 2015 by JoaMat
eggil Posted April 24, 2015 Report Posted April 24, 2015 This is very nice. Is hard to keep up with all your ideas!
Kerry Posted April 24, 2015 Report Posted April 24, 2015 (edited) Just checking the board/schematic around the servo. Looks good. You can change the label for PZTA28 to PZTA06 (same pin out) or some other NPN. Keeping the MJF15030 part is a good idea. Also, the 5K pot should probably go down to a 1K (or 2K) POT and also change the 20K to a 24K (TBD) resistor. Varying by 400 ohms moves the output about 6 - 8 volts. It's just a matter of making it have enough range, but not being too sensitive. The last thing is that I currently have 2pF caps across both legs of the 2 x 1M resistors on the KGST build. I'm not sure if this helps or hurts. I'll try pulling them out this weekend. I'm hoping the 220pF cap can manage any possible oscillation. I'll confirm the rest of the board then built the LTSpice model next. Edited April 24, 2015 by Kerry
insanity Posted April 24, 2015 Report Posted April 24, 2015 I was also justing looking at the new board and wondered if the lm4040-10 sot package couldn't be replaced by a to92 to make it easier. Furthermore could someone elaborate on the advantages of the new servo? I am really interested in that.
Kerry Posted April 24, 2015 Report Posted April 24, 2015 The net benefit is that it will have a larger operating range. 1
JoaMat Posted April 24, 2015 Report Posted April 24, 2015 (edited) / Edited November 11, 2015 by JoaMat
Kerry Posted April 24, 2015 Report Posted April 24, 2015 I just built the spice model for the Carbon and noticed the same thing. It should use a 2.5V or max 5V reference.
kevin gilmore Posted April 24, 2015 Author Report Posted April 24, 2015 (edited) certainly can replace the reference with a to92, current datasheet does not list the pinouts. I did trim the emitter resistors to 25 ohms, so there is still about 9v on the servo. But will change values to the final parts when we all decide what those are. also added a pot in series with the 20k resistor to adjust the dc to exactly zero. the 25 ohms decreases the thd a significant amount at 20khz because of the added gain. let me know which parts and values to change. Edited April 24, 2015 by kevin gilmore
JoaMat Posted April 24, 2015 Report Posted April 24, 2015 (edited) / Edited November 12, 2015 by JoaMat
kevin gilmore Posted April 25, 2015 Author Report Posted April 25, 2015 just tried it, very little actual ground plane due to all the wires. eventually when we go to all surface mount everything, the board will be at least 3 layers.
JoaMat Posted April 25, 2015 Report Posted April 25, 2015 (edited) / Edited November 12, 2015 by JoaMat
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