Hi folks...
Finally finished my layout of Grey´s "Mini-A-Schematic". Didn´t manage to make it one-sided 🙁 The schematic can be found here in the forum.
So... Are the trays thick enough? the "small" ones are 0,7 inch and the "big" ones are 1.5 inch.
Greetz...
Finally finished my layout of Grey´s "Mini-A-Schematic". Didn´t manage to make it one-sided 🙁 The schematic can be found here in the forum.
An externally hosted image should be here but it was not working when we last tested it.
So... Are the trays thick enough? the "small" ones are 0,7 inch and the "big" ones are 1.5 inch.
Greetz...
Small signal traces don't need to be anywhere near that big. You can go smaller than shown for all traces except the ones carrying power in the output. Might even allow you to make it single sided, it you really need to. The feedback trace can be small, just the output trace needs to be anywhere near that big. Same for R18 to C2, etc.
Move R16 much closer to the Gate of Q5 - like R14 and Q4.
Try rearranging so the input differential can be back to back - good thermal contact promotes offset stability. BrianGT's board used a chunk of aluminum between teh devices but if you can get them connected (with an isolator and Isolated screws) it would be helpful.
I don't have Grey's schematic, but I'll bet that there was a cap bypassing D1. A 1 uf film cap would be good, but you can go with a 10 uf electrolytic.
Why the fish hooks around R20 and R21?
Verify that the pads for your resistors are big enough to pass a lead through and still have something to solder to.
Move R16 much closer to the Gate of Q5 - like R14 and Q4.
Try rearranging so the input differential can be back to back - good thermal contact promotes offset stability. BrianGT's board used a chunk of aluminum between teh devices but if you can get them connected (with an isolator and Isolated screws) it would be helpful.
I don't have Grey's schematic, but I'll bet that there was a cap bypassing D1. A 1 uf film cap would be good, but you can go with a 10 uf electrolytic.
Why the fish hooks around R20 and R21?
Verify that the pads for your resistors are big enough to pass a lead through and still have something to solder to.
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@gruni: You´re right 😱 I´m using Eagle. The traces are 0.07mil and 1.5mil.
@Bob: Done 😛 Have a look at it...
Moved R16, added C4 for bypassing D1, reworked some traces to delete those fish hooks. Thermal contact will be established bay using a 3mm thick copper bar and good thermal greese (about 7.2W/m*K). Think that shall work
@Bob: Done 😛 Have a look at it...
An externally hosted image should be here but it was not working when we last tested it.
Moved R16, added C4 for bypassing D1, reworked some traces to delete those fish hooks. Thermal contact will be established bay using a 3mm thick copper bar and good thermal greese (about 7.2W/m*K). Think that shall work
You mean 70 mil and 150 mil or 0.070" and 0.150" 😉
Looks better. I'm guessing that you plan to use the top of the board as a ground plane.
You have plenty of room if you want to make it a bit more compact. The feedback trace R21 to R8 should be 70 mil. Same with the trace R21 to C2.
I'm curious. Why did you choose to make R12 variable? Leave a pad to place a fixed resistor once you find a gain that works for you. It sets the active current gain. R11 sets bias. That's more often variable.
There's still a fish hook at R9 R11. No big deal, but you could run the trace from C2 diagonally to R10 then up.
Be sure that the holes and pads for resistors are large enough. Eagle defaults to some really small holes and very little pad around the hole. I've had troubles with resistor leads barely fitting, some brands have larger leads than the default holes. this means you'll end up editing your components, but you're in it to learn, right?
Another thing that would make the board interesting would be to add pads for external output devices so you can make a larger Aleph if you want later.
Looks better. I'm guessing that you plan to use the top of the board as a ground plane.
You have plenty of room if you want to make it a bit more compact. The feedback trace R21 to R8 should be 70 mil. Same with the trace R21 to C2.
I'm curious. Why did you choose to make R12 variable? Leave a pad to place a fixed resistor once you find a gain that works for you. It sets the active current gain. R11 sets bias. That's more often variable.
There's still a fish hook at R9 R11. No big deal, but you could run the trace from C2 diagonally to R10 then up.
Be sure that the holes and pads for resistors are large enough. Eagle defaults to some really small holes and very little pad around the hole. I've had troubles with resistor leads barely fitting, some brands have larger leads than the default holes. this means you'll end up editing your components, but you're in it to learn, right?
Another thing that would make the board interesting would be to add pads for external output devices so you can make a larger Aleph if you want later.
Guess what... ^^
I´ll drill the holes for the parts min. +1/10mm everytime. That saves some room for changes with parts. And yes i´m still learning 😉
R12 is variable for setting DC-offset. Or am i wrong? Could bet i´ve seen this here around...
I´ll first try this one as-is, experimenting around with some parts (capacitors, resistors and transistors from different manufacturers). When done testing and fooling around, i´ll maybe go on and make a design on an Aleph 30 (think this was the next "stage"). I don´t pay anything for the PCBs. So if i mind to change something, i´ll make it^^
Luckily the postman delivered some "presents" for me 😉 25xIRF9610, 10xIRFP150 and a handful BC550C. Everthing for free. Did i mentioned that i´m also able to become some parts as "samples"? ^^ I´m in heaven for DIY XD
I´ll drill the holes for the parts min. +1/10mm everytime. That saves some room for changes with parts. And yes i´m still learning 😉
R12 is variable for setting DC-offset. Or am i wrong? Could bet i´ve seen this here around...
I´ll first try this one as-is, experimenting around with some parts (capacitors, resistors and transistors from different manufacturers). When done testing and fooling around, i´ll maybe go on and make a design on an Aleph 30 (think this was the next "stage"). I don´t pay anything for the PCBs. So if i mind to change something, i´ll make it^^
Luckily the postman delivered some "presents" for me 😉 25xIRF9610, 10xIRFP150 and a handful BC550C. Everthing for free. Did i mentioned that i´m also able to become some parts as "samples"? ^^ I´m in heaven for DIY XD
R11 is what you'd make variable for a little bit of offset control. R12 doesn't make a difference in offset.
We each make our own decisions about samples. I don't take them because I am not going to make a production item, just like I won't test drive a Ferrari as much as I would love to see what it feels like. For $100 or so I can get a decent selection of devices to match...
We each make our own decisions about samples. I don't take them because I am not going to make a production item, just like I won't test drive a Ferrari as much as I would love to see what it feels like. For $100 or so I can get a decent selection of devices to match...
No^^
I mean i get some "samples" out of our stock 😉 We produce sensors and bus-systems for automation industries. All parts which i declare as "samples" are parts from running systems 😎
I mean i get some "samples" out of our stock 😉 We produce sensors and bus-systems for automation industries. All parts which i declare as "samples" are parts from running systems 😎
Well... Back again 😉
First channel wired and what shall i say: It works^^ Runs @1A and gets hot (~50-60°C). Think that´s class a^^
Got some hum at the output... Very silent but it is there...
First channel wired and what shall i say: It works^^ Runs @1A and gets hot (~50-60°C). Think that´s class a^^
Got some hum at the output... Very silent but it is there...
Nice. Pictures, Bitte!
Concerning the hum..what does your PSU look like? Inputs shorted or open, or anything connected? And what's the load?
To correctly set the AC current gain, refer to the original Zen article (page three of http://www.passdiy.com/pdf/zen-ver2.pdf) or Aleph-X 100w Amplifier Construction Notes for a wealth of info.
Concerning the hum..what does your PSU look like? Inputs shorted or open, or anything connected? And what's the load?
To correctly set the AC current gain, refer to the original Zen article (page three of http://www.passdiy.com/pdf/zen-ver2.pdf) or Aleph-X 100w Amplifier Construction Notes for a wealth of info.
Going to make some pictures next days...
PSU is made of 100VA torroid - MUR860 - 15mF / 235mR / 15mF (per channel).
Load is an 8R Speaker, input an old MP3-Player. No Pot at the input. Hum is there with and without the MP3-Player.
PSU is made of 100VA torroid - MUR860 - 15mF / 235mR / 15mF (per channel).
Load is an 8R Speaker, input an old MP3-Player. No Pot at the input. Hum is there with and without the MP3-Player.
Hm, a total capacitance of 30mF per rail may be a little on the low side. People usually have around 60mF per rail. Maybe you're hearing ripple voltage from the PSU.
So...
After hours of listening i´ve decided to go with 1,2A.
Just one thing: After 2 hours of playing music at moderate level, the fuse is blown. It just happened after turning on the lights in my room. Anyone an idea about what happened?
After hours of listening i´ve decided to go with 1,2A.
Just one thing: After 2 hours of playing music at moderate level, the fuse is blown. It just happened after turning on the lights in my room. Anyone an idea about what happened?
Assuming that you mean the fuse in the amp's supply blew, not the house fuse.
If you test with a 100W bulb in series with the amp (the infamous light bulb tester) is the bulb bright or dim?
If the bulb is dim, I suspect that either the fuse is rated too close to the actual current draw or the bias is running away.
If the bulb is bright I suspect that you have overheated your transformer and created a short. Just 100 VA is cutting it a bit tight. I'd go with 200+ VA per channel. Check the transformer's primary DC resistance and compare it to specification.
If you test with a 100W bulb in series with the amp (the infamous light bulb tester) is the bulb bright or dim?
If the bulb is dim, I suspect that either the fuse is rated too close to the actual current draw or the bias is running away.
If the bulb is bright I suspect that you have overheated your transformer and created a short. Just 100 VA is cutting it a bit tight. I'd go with 200+ VA per channel. Check the transformer's primary DC resistance and compare it to specification.
Do you mean the house fuse for that room where you listen to your amp?
If the total consumption over the fuse is to high it gets warm, any additional consumer can blow the fuse.
Check your mains.
Regards
Sam
If the total consumption over the fuse is to high it gets warm, any additional consumer can blow the fuse.
Check your mains.
Regards
Sam
There is too much draw on the circuit. Try plugging your amp into another outlet. You need to determine what is on the circuit drawing so much current and spread the load around to other circuits.
It would also be a good idea to determine the current draw of your amp to be sure that it is behaving properly.
My brother bought an old house and found that the kitchen counter, bathroom and living room air conditioner outlets were on the same 20A breaker. The air conditioner and his wife's hair dryer were OK, but once he tried to make toast...
It would also be a good idea to determine the current draw of your amp to be sure that it is behaving properly.
My brother bought an old house and found that the kitchen counter, bathroom and living room air conditioner outlets were on the same 20A breaker. The air conditioner and his wife's hair dryer were OK, but once he tried to make toast...
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