Thanks, so you think I should go with the 10K stepped ladder attentuator volume?
I don't know why I have soo many 🙈
So I fixed the mains hum somehow by just wiring the commons from the bridge rectifiers differently... Also found out I killed one of the common terminals when I soldered it which may have been part of the issue.
Anyways, this amp has an eerily quiet background now that I fixed that - even with IEMs. RJM wasn't exaggerating about it being quiet.
Hi, what part number is this heat sink by chance? I think I'll give it a try as well.
Hi there, I sourced them from ebay, they were advertised as "5pcs 19*15*10mm Black Anodized Aluminium 781/7805 Heat Sink For TO-126 TO-220".
You can put an aluminum plate as seen in the photo. It is a simple and very effective method.
I've ordered 2.2uH inductors, 5W 3.3R resistors for the suggested modifications to eliminate hum/noise. The rest of the parts I have at home.
So, I'll wait on putting the headamp in an enclosure until the ordered parts arrive.
So, I'll wait on putting the headamp in an enclosure until the ordered parts arrive.
I wish I could, the drill press I need to make holes in the enclosure is currently not accessible as my daughters mother has put a bunch of stuff in the way 😅
I could use my regular drill I suppose...
On a Romanian television there is a series... "My husband's wife". 😉
My sapphire project is going onto the backburner for multiple reasons. For starters my Gpu died and all my budget went there and while running a psu load test to see if it can handle other hp amplifiers the transformer gave in.
@kazuviking I'm sorry to hear about your PC hardware. Especially GPU's carries a hefty price tag these days.
After an unsuccessful attempt to build one, I gave up that pcb-s, no idea what was wrong, my transistors had the same beta, npn and pnp and I was happy abot it, but it was lower than 400....290 exactly. Could this be the reason the amplifier distorted like hell? In fact one could hear a bit of signal but the distorsions were much more higher level...somehow like a torn speaker diafragm...
Now I try to build it again, on fresh PCBs from @Julian RO , but I'm looking for pnp's, I have more than 20 BC337 with beta around 435 but all my 327's are under 300 or above 500...
Like a fate irony....I have a bunch of BC309C, NOS, Tungsram made, and many of them meassure 435...should I give them a try? I know they are not directly complementary transistors....but if the amplification factor is a must, in that case I could complete the two demandings: beta over 400 and equal pairs...
Did anyone try, not especially in this setup, to match different pnp and npn's with good results?
And my last inquiry: is that bad if my BD139-140 are higher beta than 100? Let's say about 180....200? Of course I mean the finals in the signal path, for the regulator ones I have no worry....the more is the best there...
Now I try to build it again, on fresh PCBs from @Julian RO , but I'm looking for pnp's, I have more than 20 BC337 with beta around 435 but all my 327's are under 300 or above 500...
Like a fate irony....I have a bunch of BC309C, NOS, Tungsram made, and many of them meassure 435...should I give them a try? I know they are not directly complementary transistors....but if the amplification factor is a must, in that case I could complete the two demandings: beta over 400 and equal pairs...
Did anyone try, not especially in this setup, to match different pnp and npn's with good results?
And my last inquiry: is that bad if my BD139-140 are higher beta than 100? Let's say about 180....200? Of course I mean the finals in the signal path, for the regulator ones I have no worry....the more is the best there...
Waiting for a more serious answer to post #1896 I started selecting transistors. After another order I got enough transistors to make pairs, in fact I have all BC327/337 at beta between 435....439, all NPNs are 438 and the complementaries not perfectly equal, but I think 435-439 is enough close range. The final transistors are all 4 at hFE 174, some old stock C-DIL brands. Is there e real benefit to choose transistors with higher hFE for the power supply, or it's enough to use also here pairs at hFE 174 like the output final transistors? I know in theory the higher is better, but is it worth here?
I took the liberty to edit/re-draw the schematic, I didn't change anything excepting the layout, I think it's easier to follow the circuit now, especially if someone is short sighted as I am. I hope there's no offense with this redesign...it's just graphical layout stuff.
@rjm : If there are some more changed values or some mistakes in my draw, please let me know and I'll modify it. I hope this is the latest version of this amplifier. I didn't remember the original name of the power supply design, please refresh my memory if there's some specific name to it.
I took the liberty to edit/re-draw the schematic, I didn't change anything excepting the layout, I think it's easier to follow the circuit now, especially if someone is short sighted as I am. I hope there's no offense with this redesign...it's just graphical layout stuff.
@rjm : If there are some more changed values or some mistakes in my draw, please let me know and I'll modify it. I hope this is the latest version of this amplifier. I didn't remember the original name of the power supply design, please refresh my memory if there's some specific name to it.
Attachments
250 could be too much, BOM says 100 for BD139-140 hFE.... I was afraid about mine, at 174....these double the rise of amplification factor. Did anyone try such high hFE transistors? What could happen or what behaviour should be expecxted with the rise of hFE, keeping in mind that the complementaries are equal?