Digikey is better than newark IMHO. There a slab heat sink was over $100.
This 5 x 1.5" digikey one looks okay at $28 345-1176-ND 0.6 deg C/W
but I got a whole Peavey PV-4C for parts $20 plus $28 freight on E-bay. Heat sinks, fan, connectors, 130 VCT transformer, case.
LED, LCD TV's have big heat sinks, projection TV have middle sized ones, CRT tv do not. I carry a pencil box of tools in my bike & when I see something useful on the curb, I pull the covers & take the good stuff. Power cords, I used a desk fan cover on an organ volume control board to keep wandering fingers off the hot resistors.
Projection TV's have 6" speakers good for 20 W and some high power resistors.
I met my best friend in college at the equipment salvage pile behind the chemistry building.
Blown up VFD motor drives have big heat sinks & cases too. AB, TB Woods, Yakasaka, fastback brands. Lots of those in the dumpster of food plants, the sanitation workers kill them with the washdown hoses. Visit a bar near a food plant after shift change, buy a maintenance man or cleanup worker a beer. He might scrounge one or three for you.
The guy that proved spooky interaction aka quantum entanglement is (probably) real at 3 meters was a physics storeroom scrounger. He said so right on Nova on PBS last month.
This 5 x 1.5" digikey one looks okay at $28 345-1176-ND 0.6 deg C/W
but I got a whole Peavey PV-4C for parts $20 plus $28 freight on E-bay. Heat sinks, fan, connectors, 130 VCT transformer, case.
LED, LCD TV's have big heat sinks, projection TV have middle sized ones, CRT tv do not. I carry a pencil box of tools in my bike & when I see something useful on the curb, I pull the covers & take the good stuff. Power cords, I used a desk fan cover on an organ volume control board to keep wandering fingers off the hot resistors.
Projection TV's have 6" speakers good for 20 W and some high power resistors.
I met my best friend in college at the equipment salvage pile behind the chemistry building.
Blown up VFD motor drives have big heat sinks & cases too. AB, TB Woods, Yakasaka, fastback brands. Lots of those in the dumpster of food plants, the sanitation workers kill them with the washdown hoses. Visit a bar near a food plant after shift change, buy a maintenance man or cleanup worker a beer. He might scrounge one or three for you.
The guy that proved spooky interaction aka quantum entanglement is (probably) real at 3 meters was a physics storeroom scrounger. He said so right on Nova on PBS last month.
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It's actually funny you say that, I have one of these TVs that I salvaged from my girlfriends apartment. They got a new one and I was like "hmm maybe I can salvage some expensive transformers or whatever. I haven't opened it up yet, but I've been waiting for a good cause.
EDIT: Says here there are 20W speakers in there, maybe will use those for next project. I want to go discrete this next time around, no op amps, really get into the nitty gritty.
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Oh, yeah, a 42" plasma TV ought to be chock full of heat sinks. Big FET's too, but switching, not linear lateral fets. Discharge the mains caps with a rubber covered clip lead before fooling with it. Might be just the mains e-caps are blown: that was what was wrong with the 50" I salvaged but the screen was broken when the previous owner pitched it on the curb. I don't have room for a 50" TV anyway.
Here is my AX6 70w/ch project in a dynaco ST-120 case & transformer. Post #212 Retro Amp 50W Single Supply - Page 22 - diyAudio
I'm listening to it right now, while washing dishes then surfing the web. Great sounding, puts out 70 W/ch for a 1/4 second at a time, probably more peak wattage values I didn't measure with the scope I don't have. I regulated the input transistor voltage with zeners, which is not Bob Cordell approved but uses a whole lot less parts & wires. No room in that chassis for 2 honeybadger boards and a dynaco ST-120 transformer is not center tap anyway.
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I looked at school, no heatsinks to be scavanged. I'm going to take a look some more at digikey, create a little checksheet, you can vet that and tell me if I'm off or not. I really do need to open up that TV, by the way, it works perfectly fine, they just got rid of it.
I'm looking to order parts this weekend maybe, maybe next, we'll see. I'll reply again with an updated list. Thanks forall your help. SChools going insane right now, haha.
Hey,
I'm looking for a good heatsink that I can drill holes into for the output transistors. is this good?
The heatsink I linked to in post 61 was 0.6 degC/w for $28
The one in post 65 is 1.8 degC/W for $26
Higher resistance is bad. The wakefield has a forced air resistance of 1.1 degC/w at 500 LFM , but how much do you want to spend on a fan? You're not going to get 500 LFM out of a $19 fan.
The heatsinks asuslover has are big enough, but you have to pay for 2 @ $30, and you have to pay separate shipping from his house, which you don't have to pay at digikey since you were going to buy stuff anyway.
Beware of digikey's standard shipping from fedex. Fedex surcharges a residence fee, which may show up later on your bill even though they quote $8.99 flat rate. I suggest USPS priority, especially if you have a big enough PO lockbox at your apartment. Fedex leaves stuff at the back door in the rain at my house, even though I have a covered porch in front.
The one in post 65 is 1.8 degC/W for $26
Higher resistance is bad. The wakefield has a forced air resistance of 1.1 degC/w at 500 LFM , but how much do you want to spend on a fan? You're not going to get 500 LFM out of a $19 fan.
The heatsinks asuslover has are big enough, but you have to pay for 2 @ $30, and you have to pay separate shipping from his house, which you don't have to pay at digikey since you were going to buy stuff anyway.
Beware of digikey's standard shipping from fedex. Fedex surcharges a residence fee, which may show up later on your bill even though they quote $8.99 flat rate. I suggest USPS priority, especially if you have a big enough PO lockbox at your apartment. Fedex leaves stuff at the back door in the rain at my house, even though I have a covered porch in front.
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I think this is the one you were referring to in post 65? It's not on digikey, so gotta find some shipping options. also all the sites I've seen this one on are in the uk....
EDIT: I should really open up that TV.
Awesome. What do you think about this? I chose all ceramics, except for the 2200u at the output. Is there a general rule of thumb about when you can get away with electrolytics? I'm still fuzzy on that. Anything not in the BOM is something I can easily get at school or I have at home, even some of the resistors I have I just thought I'd get a few extra.
Notice that I screwed up on two of the resistor ones, must have selected the minimum quantity 1000 option, but I'll fix that. Pic attached, and the xlsx as well, for easier selection of the digikey number.
Attachments
Makes sense what you are saying,
So for who is interested I could sell 1 heatsink for 15$ +15$ shipping =30$, not bad deal but buying 2 of them would make more sense.
Sorry for interrupting .
BOM looks mostly good. You may exceed the voltage on the 100 uf 6.3 v ceramic cap & blow it up. NP electrolytics go higher voltage, like 50 or 100. I can't believe 4.7 uf ceramics are $2.49 now, last time I ordered some they were $5. Lots of people on here sneer at ceramics in the sound path. I think the speakers cover up all that little distortions. I'm using ceramic as the input cap to my 6 hour a day amp, but a COG 50 v one which should be more linear at 1 vac signal than x7r dielectric.
You're missing the zobel network on the output, which keeps your speaker from acting as a radio antenna and injecting RF into your amp. 10 ohm 3 W resistor, parallel 14 turns wire around a AA battery or suitable non-metal form (dowel rod, china marker). You'll need to order the 10 ohm resistor.
Does your school have the male banana plug for your speaker?
You're missing the zobel network on the output, which keeps your speaker from acting as a radio antenna and injecting RF into your amp. 10 ohm 3 W resistor, parallel 14 turns wire around a AA battery or suitable non-metal form (dowel rod, china marker). You'll need to order the 10 ohm resistor.
Does your school have the male banana plug for your speaker?
Like just the male header? I'm sure they do, I'll check right now.
EDIT: Here's the 10 ohm resistor, I'll put that in. need to look at what a zobel network is one second.
EDIT2: So I looked up a zobel, I see usually it's done with a capacitor, does it matter in this case? 14 turns around any nonmetal/conducting "rod-like-shape" seems to be the inductor in series with the 10 ohm all in parallel with the speaker, correct?
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Okay cool, I'll put that in simulation and will check it out.
Two questions I'm wondering about now as I'm getting close to finalizing some stuff:
1. For a stereo mix, I'm guessing running to two of these from the same source isn't really plausible, or maybe, not plausible for my 30V 1.2A power supply. If I got a supply that could handle ~3 A of current, could it work then? I'm assuming here I'm going to get a mono mix out of superimposing the L and R channel into one input.
2. I looked at my power supply and the spec sheet says 150 mV pk-pk of noise. I'm trying to think of what LC lowpass to put right after the supply, but before the voltage divider, but I'm worried about using correct LC values and to not drop a fat resonance spike right in my mag response. I realize that putting an L and C there basically makes a resonant circuit out of that portion. There's a resistance there and I might need to do some simming to figure out what it is, then I'd know that resistance and can design the L and C values accordingly. The other issue there is that I have attenuation from the LC lowpass, and I'd have to change up some stuff in the gain stage to compensate for that. I'm wondering if there's some L and C values that are "big enough", and I don't have to worry about this, but let me know what you think.
I thought you were committed to monaural, due to your single speaker.
You can't junction the two outputs of a radio, cd player or cellphone, without damaging them. What one does to make a mono signal is run each input through a 1 k resistor, then join them at the outlet. This circuit has a 10 x gain, which should be enough to get full power out (~12 vac) with that input arrangement.
You can't buy cheap inductors of a defined inductance. I believe you said you were going to wind 22 turns around a toroid on your power input or something? I had in mind a big coil part of a old TV tuner I am parting out, but picking up one on the street is now non-productive because of the $10 disposal fee on the CRT tube. I put a 22 turn choke out of a PCAT power supply in my disco mixer to kill all noise coming in on the DC line. Followed by a 1000 uf cap, a 1 ohm resistor, another 1000 ohm cap, for a pi filter. The addition of second stage cap finally got rid of the hum. For a power amp, you'll need more than 1000 uf filters on the DC input, I imagine.
Really, a visit to a charity resale shop is in order. There are 32 v 2.5 A power supplies available from scrapped out copier/printer/fax machines that sell for about $2. Only Salvation Army around here messes with selling that stuff, the others just send that stuff to the landfill. I bought several when they contained a transformer, which was guarenteed not to produce nasty RF output. Shops that have those might also have car speakers for $4 or so, with the impedance shown right on the back. 4 ohms is too low for TIP41 outputs, IMHO.
If you insist on buying new, I imagine digikey has 24 vac 2 amp wall transformers. I just bought a 16 vac 2 amp one for $23, for my PV8 mixer which came without a supply. I also just bought a load of 26 VAC ct 2 A transformers from electronicsurplus.com for $8 each, to fill out the box because I bought MPSW06 transistors from them. The freight was $9 with or without the 20 lb of iron. 26 vac can be regulated down to 30 v peak with some diode or triac droppers in series with the output. I need 3 more 20-30 W amps to amplify TV in town (samsungs sound horrid, buy the $190 sound bar!!) and hear the 1W FM radio out at my summer camp so I can hear it outside.
You can't junction the two outputs of a radio, cd player or cellphone, without damaging them. What one does to make a mono signal is run each input through a 1 k resistor, then join them at the outlet. This circuit has a 10 x gain, which should be enough to get full power out (~12 vac) with that input arrangement.
You can't buy cheap inductors of a defined inductance. I believe you said you were going to wind 22 turns around a toroid on your power input or something? I had in mind a big coil part of a old TV tuner I am parting out, but picking up one on the street is now non-productive because of the $10 disposal fee on the CRT tube. I put a 22 turn choke out of a PCAT power supply in my disco mixer to kill all noise coming in on the DC line. Followed by a 1000 uf cap, a 1 ohm resistor, another 1000 ohm cap, for a pi filter. The addition of second stage cap finally got rid of the hum. For a power amp, you'll need more than 1000 uf filters on the DC input, I imagine.
Really, a visit to a charity resale shop is in order. There are 32 v 2.5 A power supplies available from scrapped out copier/printer/fax machines that sell for about $2. Only Salvation Army around here messes with selling that stuff, the others just send that stuff to the landfill. I bought several when they contained a transformer, which was guarenteed not to produce nasty RF output. Shops that have those might also have car speakers for $4 or so, with the impedance shown right on the back. 4 ohms is too low for TIP41 outputs, IMHO.
If you insist on buying new, I imagine digikey has 24 vac 2 amp wall transformers. I just bought a 16 vac 2 amp one for $23, for my PV8 mixer which came without a supply. I also just bought a load of 26 VAC ct 2 A transformers from electronicsurplus.com for $8 each, to fill out the box because I bought MPSW06 transistors from them. The freight was $9 with or without the 20 lb of iron. 26 vac can be regulated down to 30 v peak with some diode or triac droppers in series with the output. I need 3 more 20-30 W amps to amplify TV in town (samsungs sound horrid, buy the $190 sound bar!!) and hear the 1W FM radio out at my summer camp so I can hear it outside.
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I have about five of these at home, and for a simple project like this I was going to use them as my speakers. I was designing for one speaker, but I completely forgot that for a real project it would be nice to do two and have a stereo mix. SO now I'm trying to consolidate everything I know and either do something tricky and get it to work stereo, or just upgrade my supply and build two of them.
I don't have an issue going to the salvation army, or goodwill to scavange some stuff. I really need to open that TV, I bet I'd find some good stuff there. I might go do that right now actually.
If the TV worked I wouldn't scrap it, but if it is a boat anchor, oh yeah. Modern TV's have a hash filter before the switcher power supply that has the 22 turn choke all ready there to be salvaged. Also a 300 VAC MOS filter after the fuse, which soaks up those nasty 1000 VDC spikes that come out of heating/AC motors when they shut off. Those are a blue disk, the marking with the wiggle is how much AC they can stand all the time.
Your 1.2 A supply could supply two channels at 2.8 W each. (0.6 a^2 * 8 ohm) That is only 6 db softer than 10 W. So do the experiment, then search for the bargain 30 v 2.5 A supply later. The experiment might be a big failure to start with. My LM1875 amp was a big failure, motorboats irreduceably. The $2 LM1875 kits on e-bay have direct coupled IC to speakers, which is a speaker damage hazard IMHO. I was planning to use my $120 ea (used) Peavey 1210 speakers in my TV room, no speaker burner boards will be connected to those. There are more Apex AX6 in my future, only thing that 2 of will fit in that box I built.
Your 1.2 A supply could supply two channels at 2.8 W each. (0.6 a^2 * 8 ohm) That is only 6 db softer than 10 W. So do the experiment, then search for the bargain 30 v 2.5 A supply later. The experiment might be a big failure to start with. My LM1875 amp was a big failure, motorboats irreduceably. The $2 LM1875 kits on e-bay have direct coupled IC to speakers, which is a speaker damage hazard IMHO. I was planning to use my $120 ea (used) Peavey 1210 speakers in my TV room, no speaker burner boards will be connected to those. There are more Apex AX6 in my future, only thing that 2 of will fit in that box I built.
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Yup I'm ready for this project to potentially fail, but that's totally okay.
So I opened up the TV.... Seems like there's a treasure trove of good stuff in here. Tons of power resistors, heat sinks, MASSIVE caps. I've been watching some videos how to safely dismantle the TV and get the boards out and discharge the caps. I don't mind that it works, they needed to get rid of it, I don't really want it, and this is a learning experience in scrapping for me, I bet I can get more than the $100 I'd be selling it for on craigslist.
Heres some pics
Sell it, there are dead TV's on the curb all the time. A liltte rain doesn't hurt the stuff you want. Don't salvage the electrolytic caps, those are usually what kills the TV. You short the caps on the input with alligator clip leads, also series a ~47 ohm resistor if you don't like the snapping noise. But rubber covered alligator clip leads have gone from a $3 for 12 item to $14 each sold by pamona, it seems. And that clip is only on one end. I couldn't find any clip lead kits at newark or digikey either recently. Yeah, you can kill yourself with one if you expect the cheesy rubber to insulate off 600 V. **** lawyers!.
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