Excellent update.....many thanks. Don't forget, if you just need cheap, you can parallel two of those pass transistors and they are very cheap. Great idea of using a variac to test the effects of reduced voltage of the transformer on the op amps.
DO NOT tin the tip of stranded wires for a screw block! The softer metal of the solder will crack & bend over time, and allow the original tightened screw position to lose pressure on the wire as a whole. Then you either eventually get a lost connection or a high resistance connection. In the worst case this has happened to many people running 3D printers and left their house burnt to the ground. Common cause was tinned wires screwed into screw blocks; come loose on the heater connection and you are running amps through a high resistance point. The assemblers were following the same convenience advice as you. You'll see most 3D printer reviewers now checking if connections are crimped into 3D printer motherboards for cheaper models. Better than tinning is indeed screwing down the bare wires. Because the wires are stronger less ductile metal, even though it could be messy, the screw can hold pressure on them even when they are nudged. Even better than that, is using an appropriate crimp connector, crimping it on, and then screwing down on the crimp.
I get what your saying and agree, however in the case here I am only tinning the first mm or so. This should go past the clamp point. If it does not then this method should not be used.
Loads of changes ! it's very interesting, you could redesign it and get a PCB made but that's not the point I guess. Great stuff and I would use something a bit more beefy as the pass trany and I would not pay 30 anythings for an Op Amp LOL ! The wire tip is great for hobbyist but industry won't like it, here in the UK its a no no as eventually the terminal loosens with soft solder and the aerospace and medical people stopped it, see you in the next one....cheers !
Good thoughts. On the soldering the wire, that's why just the very tip. Then the solder goes in past the clamping point and actually acts like a anchor. Tinning to whole stripped length is a no no for sure.
I always soldered the tip for years. I started using bootstrap ends just this year. The relief the plastic bit that extends from them makes things much tidier. Only for screw in terminals. I still solder everything else. I despise those push in proto boards.
While you're reading 36v open circuit, at 3A you should be at least halfway to the transformer's rated voltage (@6A), or ~30v, probably more like 28v. That's still 75W of heat when outputting 3v@3A, but not the borderline 100W.
I solder tinned the tips, for years, for this application. I have recently purchased a ferrule crimping set. The mechanical hold/purchase of the screw terminal on the ferrule is much better, IMO. I was concerned that I was wasting my money on the set, but I find it to be a worthy investment that gives satisfaction, when used.
Ferrules are probably best if you can get the right combination. In this case I was using #18 wire and these not so good terminals would not open enough to accept the wire with the ferrule. For most purposes both methods are way better than not using anything at all.
@@t1d100 if you have a tinned lead not just the tips, it becomes a serious fire hazard. I was told this 45 years ago during my apprenticeship, and I never really beloved it until I went to pull out a plug and it was hot. Tinned wires under a screw terminal, you could see where the solder had migrated away under the pressure of the screw, then it started to arc and generate heat. I was very lucky to find this, worse it was in a commercially bought mains extension board. A crimp on or solder of ferrule is fine and the way to do things. Andy
I have a couple of cores rated for somewhere between 1000 and 2000 watts at 60 Hz AC, probably a lot closer to 2000 Watts. I'm planning on winding one as both an isolation transformer for the bench, and a 50 V supply for a HF linear amp. Should be fun, but it will take me a while with my old hands. Winding big toroids with heavy wire is hard work
@@uni-byte, I believe the operative word is 'dumber' not 'better'. I can at least cheat on the job since the primary is already in place. I got 4 transformer cores or QA failed complete transformers (slight mechanical hum or vibration problems,) from a local very high-end audio amplifier manufacturer. They took $15 for them all for the employee beer fund. Similar ones on eBay were selling for $160 each. So I'll remind myself of that as I'm busily ruining my hands and wrists.
Excellent update.....many thanks. Don't forget, if you just need cheap, you can parallel two of those pass transistors and they are very cheap. Great idea of using a variac to test the effects of reduced voltage of the transformer on the op amps.
Thanks!
DO NOT tin the tip of stranded wires for a screw block!
The softer metal of the solder will crack & bend over time, and allow the original tightened screw position to lose pressure on the wire as a whole. Then you either eventually get a lost connection or a high resistance connection.
In the worst case this has happened to many people running 3D printers and left their house burnt to the ground. Common cause was tinned wires screwed into screw blocks; come loose on the heater connection and you are running amps through a high resistance point. The assemblers were following the same convenience advice as you. You'll see most 3D printer reviewers now checking if connections are crimped into 3D printer motherboards for cheaper models.
Better than tinning is indeed screwing down the bare wires. Because the wires are stronger less ductile metal, even though it could be messy, the screw can hold pressure on them even when they are nudged.
Even better than that, is using an appropriate crimp connector, crimping it on, and then screwing down on the crimp.
I get what your saying and agree, however in the case here I am only tinning the first mm or so. This should go past the clamp point. If it does not then this method should not be used.
Loads of changes ! it's very interesting, you could redesign it and get a PCB made but that's not the point I guess. Great stuff and I would use something a bit more beefy as the pass trany and I would not pay 30 anythings for an Op Amp LOL ! The wire tip is great for hobbyist but industry won't like it, here in the UK its a no no as eventually the terminal loosens with soft solder and the aerospace and medical people stopped it, see you in the next one....cheers !
Good thoughts. On the soldering the wire, that's why just the very tip. Then the solder goes in past the clamping point and actually acts like a anchor. Tinning to whole stripped length is a no no for sure.
I always soldered the tip for years. I started using bootstrap ends just this year. The relief the plastic bit that extends from them makes things much tidier. Only for screw in terminals. I still solder everything else. I despise those push in proto boards.
I agree, ferrules only for screw terminals. I still use solderless breadboards for quick and dirty "try outs".
While you're reading 36v open circuit, at 3A you should be at least halfway to the transformer's rated voltage (@6A), or ~30v, probably more like 28v. That's still 75W of heat when outputting 3v@3A, but not the borderline 100W.
Correct!
I bought a ferrule crimper set to use with wires going into terminal blocks but I like your soldering method better.
I solder tinned the tips, for years, for this application. I have recently purchased a ferrule crimping set. The mechanical hold/purchase of the screw terminal on the ferrule is much better, IMO. I was concerned that I was wasting my money on the set, but I find it to be a worthy investment that gives satisfaction, when used.
Soldered wires in terminals is a bad idea due to the cold creep the solder experiences. Hence, *just the tip*
Ferrules are probably best if you can get the right combination. In this case I was using #18 wire and these not so good terminals would not open enough to accept the wire with the ferrule. For most purposes both methods are way better than not using anything at all.
@@t1d100 if you have a tinned lead not just the tips, it becomes a serious fire hazard. I was told this 45 years ago during my apprenticeship, and I never really beloved it until I went to pull out a plug and it was hot. Tinned wires under a screw terminal, you could see where the solder had migrated away under the pressure of the screw, then it started to arc and generate heat. I was very lucky to find this, worse it was in a commercially bought mains extension board.
A crimp on or solder of ferrule is fine and the way to do things.
Andy
I have a couple of cores rated for somewhere between 1000 and 2000 watts at 60 Hz AC, probably a lot closer to 2000 Watts. I'm planning on winding one as both an isolation transformer for the bench, and a 50 V supply for a HF linear amp. Should be fun, but it will take me a while with my old hands. Winding big toroids with heavy wire is hard work
I can't get my hear around winding a whole transformer on a toroid ring. You're a better man than me!
@@uni-byte, I believe the operative word is 'dumber' not 'better'. I can at least cheat on the job since the primary is already in place. I got 4 transformer cores or QA failed complete transformers (slight mechanical hum or vibration problems,) from a local very high-end audio amplifier manufacturer. They took $15 for them all for the employee beer fund. Similar ones on eBay were selling for $160 each. So I'll remind myself of that as I'm busily ruining my hands and wrists.
@@johnwest7993 LOL!
Mine came with OP08 which is a bit better than TL081 but I replaced them with MC34071 that can handle up to 44V supply and they are very cheap.
Did you find some DIP-8 MC34071s or use a breakout board?
I got DIP8 from AX and they are working great