DIY Amplifier Suggestions - on a tight budget

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#83
one last question before i order from partsconnexion

they have the 10k, 1% 1W Riken resistor
but they don't have a 220k Holco 1/2W/1% .. they have a 200k and a 237k one

now .. they do have a 220k 1/2W 1% Riken resistor, should i just get that?
 
#85
Jack...we pay a fortune for test equipment like that here in Canada....that power supply you showed would go for atleast 200 CAN here..............and partsconnexion...nice products....but they are the most expensive place I`ve seen....I buy from other places and their store is a half an hour away


Cheers!!The DIRT®
 
#86
elizard said:
one last question before i order from partsconnexion

they have the 10k, 1% 1W Riken resistor
but they don't have a 220k Holco 1/2W/1% .. they have a 200k and a 237k one

now .. they do have a 220k 1/2W 1% Riken resistor, should i just get that?
Click to expand...

I used Holcos in one of my first amp, but after that I'm using 220K Rikens from Parts Connexion. It doesn't matter what the value really is, 200K is good too😉

I had Vishay S102 in that location as well. 200K cost around $28 for one, but eventually I think I prefer Riken, as being more open, detailed and fast. My friends didn't like Vishay as being too laid back.
 
#87
well well .. i got all the digikey stuff, in satisfactory condition
plus it was overnight shipment for $8 .. THAT'S freakin cheap 🙂

i just ordered the stuff from partsconnexion .. hope they get the order right
they weren't quite as friendly as plitron to order from, but bleh .. so long as the order is right, i'm satisfied 🙂

now the only thing i'm going to be waiting a WHILE for is the torroid .. i'm gonna die waiting 4-5 weeks!!!

i think maybe i'll design the chassis while waiting

which reminds me .. Peter, do you have the dimensions of the 400VA torroid from plitron?
i'd need the diameter and the heights of it .. i know its 4kg .. yikes 🙂

gonna work with possibly 5mm aluminum if i can find some cheap 🙂
 
#88
ultra-low budget gainclone

Hmmm... It seems this is the place that I can post what I'm doing these days. I'm building a ultra-low budget Gainclone while I'm thinking/reading some tube related stuffs.
Attached is an LM3875-based "unity gain" gainclone which will be used as a PC soundcard amplifier. As stated above, this is an ultra-low budget project. So, there is no Blackgate, Holco, Riken, etc. Just cheap 0.22uF polyester bypass film caps, 2200uF electrolytic caps from Allelectronics, metal film resistors from Digikey, Transformer from PartsExpress, etc. I'll have to drills some holes on the chassis tomorrow. Cutting a square hole for AC power connector is always a pain. ?:bawling:

Elizard,
How's your work going? Any progress on chassis design?
 

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#89
no, haven't actually designed anything yet ..
i don't have all the parts .. i didn't receive the partsconnexion stuff yet (resistors/4.7uF cap) .. and i don't have the transformer

i did build one power cable that'll go from the PS to the GC .. wow .. took a LOT of work (2 hands, no vice .. painful to solder the connections) .. but one is done
i ended up using 22g magnet wire .. works fine so far 🙂

but i've exams monday, so can't spend time on this till i'm done that 🙂

i'm planning on the above idea as far as the chassis goes .. an opening for the toroid 🙂
should be interesting
 
#90
well .. so far so good 🙂
sorta

i just finished making the power cables .. boy they're a pain in the rear if you don't have a vice (or someone else) ..
one unfortunately turned out about 2"-3" longer than the other somehow, but whatever .. its just dc current anyway, shouldn't be a big deal
not like its a signal .. although it would have been nicer had they been equal .. but meh ..

the way i made each cord is from 4 lengths of 22g magnet wire from ratshack, each soldered to the pins on the 4 pin connectors (that's the hard part)
then i isolate each soldering w/ some heatshrink tubing, and run it through some cat5 tubing (i took out the cat5 wires and ran the magnet wire through that .. works fine except its a little loose, but provides for good flexibility!) ..
i'm gonna get a digicam soon from a friend and post some pics .. maybe i'll wait till i get everything

now i'm gonna go take my dvd player apart .. i think it has like a very small 9v transformer inside .. which would do great for the LED 🙂
no need for extra windings 😛
 
#91
update:

i just received the parts from partsconnexion, very good .. everything was in order, and i was charged less than i thought i would (i guess they don't have a minimum $25 order for canada?)

so .. tomorrow, or wednesday possibly, i will start the construction of the amp minus the transformer .. i will try to make the layout for everything, solder what needs to be soldered, bolt the rest, and hopefully all goes well 🙂
 
#92
oh, and to make things better (totally unrelated) i've picked up a beatles best-of record (67-70), two pink floyd records (final cut, and dark side .. dark side includes the 2 posters and the sticker!!!) and a jeff beck record (beck-ola), all for $20CAD 🙂
not too shabby i'd say .. all records in mint shape, the beatles ones have a bit of pops, need a little cleaning, but overall VERY good

now if only i could do good on my last exam today .. already wrote one, one more to go .. pain!!! 🙂
 
#95
The LM3875T (more common?) has a non-isolated tab...the metal part sticking out...the LM3875TF's tab is plastic...meaning it's isolated...honestly though...you could get those chips for free from national's samples program...I used it and build my first GC for under SGD$100...nice sound...however lacking bass...any idae how to beefen it up??
 
#98
And if you aren't using a grounded heatsink and you don't isolated the LM3875T, thouching the heatsink makes you go poof.

You'd have to use insulating pads with the LM3875T. I find it much easier and just plain better to use the LM3875TF, simplifies it alot.
 
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