I bet you a Euro to a dollar that you STILL use your own national currency in your mind to evaluate any and all transactions. I am so old that I still use paper and wooden pencils to make notes. And I beat most people I know with calculators at "Round" figuring numbers with only my brain. Old age and treachery beats youth and skill every time. I am treacherous to myself, I can not remember what it is I forgot.
I would not know how, in my fondest dreams, to go to the hardware store and get some 12 / 2 with ground to wire up a house, if I had to do it in Metric...
Working on the vertical MOSFET version and haven't cracked it for a way of mounting the BD140 to the main heat sink the proper way that works with the rest of the layout. Didn't spend much time on the lateral version lately, though I did realize I left out the 0.47 cap across the bias voltage spreader in my layout version schematic. That has been corrected and a cap has been put into the layout (in my local copy).
Dadod, earlier in this thread you suggested your regulated OPS PSU with comprehensive protection in addressing my concern about safety of the gate protection zener diodes and the driver transistors in the event of output short circuiting to GND. It seems to me the PSU circuit will shut down its output in such an event, but it does not seem to do anything to the stored energy in the 4x 1000uf capacitors downstream. It appears the stored energy will be up to the MOSFETs, being turned hard on due to an open feedback loop, to dissipate. Would you think the output MOSFETs will be able to discharge the caps quickly and safely enough? I haven't built and tested many amps, my experience cannot tell me much. Thanks.
PCBs has a thickness of at least 1.6mm and you want about 1mm minimum tip of the leads sticking out of the PCB surface for good soldering and reworking properties. Also out of the 8mm after the forming point, about 2mm is spent in getting even to the level of the MOSFET package surface.
It does not matter if one or two point soldered, it's up to you what is better for your layout.
Attached is max dissipations(on the verge of clipping) of the drivers and the Q6 and Q8. What is small heath sink thermal resistance?
Attachments
Nattava, that is why I put in my schematic 4 x 220 uF capacitors not 4 x 1000 uF, I think that we don't need 1000 uF caps there specialy if regulated power supply is used, and I think that the output MOSFETs will withstand discharge of those caps.
Neither did I bult and tested so many amps, but I never had a problem with discharging caps destroying output transistors, as I never use to big caps directly on the amp board. If simple power supply was used with bank of big caps I put a fuse between.
BR Damir
Pretty bad comeback when Damir's country hasn't moved to the Euro.
Best wishes
David
Yeah you are right, they went to the Metric System...
along with the rest of the world...Metric in the USA well, it is done in secret, for Enginerring types only. I still do my boards in imperial. Routing/vias on a 1mil grid. Somehow routing/via on a 0.0254 mm grid seems unnatural to me. I guess I could change to a 0.025 mm grid. Most new pkgs are done in mm. Converting back and forth is a PITA. Do the footprints in the part drawings controlling dimensions but stick to one place outline dimension type. I choose 25 mil. Smallest place grid I use is 5 mil, but only at the very last for really tight stuff. Good enough for 0.5mm pitch parts.
I like to have my parts in hand, or mechanical samples during layout , so that you can check/plan, print out 1:1 of the layout top layer = sanity check. If not possible meticulously check your libraries (symbols/footprints)
Krisfr what CAD package are you using?, if it is free I'll give it a look, WTH, learn another layout pkg.
I like to have my parts in hand, or mechanical samples during layout , so that you can check/plan, print out 1:1 of the layout top layer = sanity check. If not possible meticulously check your libraries (symbols/footprints)
Krisfr what CAD package are you using?, if it is free I'll give it a look, WTH, learn another layout pkg.
I am happy to use whatever rule is convenient, maybe 0.1 inch for DIP or 1 mm for SI parts.
But "mil" is a dumb term, millimetre? thousandth of an inch?
That's the kind of stuff that lost the $125,000,000 Mars Orbiter.
In spoken communication I use "thou.", as in "needs a thou. clearance", for the imperial stuff, still common here.
Is there some preferred way to keep this clear in the forum?
Best wishes
David
From my military days... Does anyone here know the meaning of RCH and also use the term, "Close enough for Government Work". These are great for measuring the distance from DC to Daylight.
Well I am going to end all the confusion today or tomorrow. Stand by for assumptions, opinions and guesses.
And I still do not fully understand the ppm percentage Total harmonic distortion gibberage. Give me .00000X not X ppm
Well I am going to end all the confusion today or tomorrow. Stand by for assumptions, opinions and guesses.
And I still do not fully understand the ppm percentage Total harmonic distortion gibberage. Give me .00000X not X ppm
Last edited:
Abacom's Sprint Layout 6.0, I got it on sale for about 40 dollars American. It is not a real professional product, but it serves the DIY and amateurish dabblings I do. I find it relaxing, even with its shortcomings.
From my military days... Does anyone here know the meaning of RCH and also use the term, "Close enough for Government Work". These are great for measuring the distance from DC to Daylight.
Well I am going to end all the confusion today or tomorrow. Stand by for assumptions, opinions and guesses.
And I still do not fully understand the ppm percentage Total harmonic distortion gibberage. Give me .00000X not X ppm
OK 22 ppm is 0.0022%!
I can conjure up my brain to understand that after a while. But my Digital side says to just me, I am thinking in MICRO seconds on a wave form. To me the Million part of this means micro seconds. Therefore my scope probe portion of my mind sees 22 micro seconds and not the ppm. So for sometime I misunderstood 22 parts per million ppm as .000022. Forgive my total crazyness it is just dementia setting in a little earlier than I want it to.
And yes I think of thou as in milliseconds...go figure. One part per thousand is .001 to me.
Overshoot?
I did a transient simulation with 0.4Vp-p 1KHz square wave imposed over a 100Hz 1.85Vo-p Sine, and there was overshoot at the transitions at the output. The picture attached shows the positive going transition only but the behavior at the negative going transition was identical. It appears the amp has a hard time responding even not so quick an edge -- the LPF was in place at the input, although no ringing was found. Out of curiosity I gave the similar dose of signal to Dadod's TT-TMC amp and it appears to behave much better, no signs of either overshoot or ringing. Does this indicate any problems with the CFA design, at least with my local copy of the schematic? Should I be woried about such behavior? Dadod, can you kindly do the same simulation with your schematic when you have a chance and see if it duplicates? Thanks!
I did a transient simulation with 0.4Vp-p 1KHz square wave imposed over a 100Hz 1.85Vo-p Sine, and there was overshoot at the transitions at the output. The picture attached shows the positive going transition only but the behavior at the negative going transition was identical. It appears the amp has a hard time responding even not so quick an edge -- the LPF was in place at the input, although no ringing was found. Out of curiosity I gave the similar dose of signal to Dadod's TT-TMC amp and it appears to behave much better, no signs of either overshoot or ringing. Does this indicate any problems with the CFA design, at least with my local copy of the schematic? Should I be woried about such behavior? Dadod, can you kindly do the same simulation with your schematic when you have a chance and see if it duplicates? Thanks!
Attachments
I can conjure up my brain to understand that after a while. But my Digital side says to just me, I am thinking in MICRO seconds on a wave form. To me the Million part of this means micro seconds. Therefore my scope probe portion of my mind sees 22 micro seconds and not the ppm. So for sometime I misunderstood 22 parts per million ppm as .000022. Forgive my total crazyness it is just dementia setting in a little earlier than I want it to.
And yes I think of thou as in milliseconds...go figure. One part per thousand is .001 to me.
Yes, but 0.0022% is percent, so it is 0.022 per thousand and 22 per milion or 22 ppm.