08-05-2021, 10:39 PM
@dmozell - A very good discussion on the pitfalls in powering low voltage devices especially in the context of the current practice of powering devices from USB 5v supplies.
I have encountered problems with USB Cables for several years now, ever since the supply requirement went up to 2.1Amps. I have given up on trying to buy USB cables to use in Charging or Power Supply applications and now treasure my accumulated collection of cables that came with original equipment.
I have disected many cables and have discovered that most of the cable is NOT Copper but CCA (Copper Clad Aluminium)! This is ductile enough to be drawn into very fine and then stranded wire which is usually crimped at the ends. This is even more common in Cat5 and Cat6 patch cables with IDC terminations. Whereas it is possible to solder CCA wire, you have to be careful not to scrape the conductors because if you do, it will expose the Aluminium core which oxidises to a black mess when it comes in contact with activated Flux. Having said that, I have managed succesfully to solder CCA by carefully stripping the insulation and soldering very quickly with a good Rosin cored Solder.
As an aside, If you examine the connections from the incoming BT Cable to your Master Socket, you will probably find that the incoming Pair is crimped using "Jelly" (Gel filled) Crimps to a short pair od tail befor connection to the Master Socket A & B Terminals. I believe this to be because BT installed a lot of Aluminium cable in the 70's and 80's which corrodes very quickly when in contact with other metals and moisture.
I have encountered problems with USB Cables for several years now, ever since the supply requirement went up to 2.1Amps. I have given up on trying to buy USB cables to use in Charging or Power Supply applications and now treasure my accumulated collection of cables that came with original equipment.
I have disected many cables and have discovered that most of the cable is NOT Copper but CCA (Copper Clad Aluminium)! This is ductile enough to be drawn into very fine and then stranded wire which is usually crimped at the ends. This is even more common in Cat5 and Cat6 patch cables with IDC terminations. Whereas it is possible to solder CCA wire, you have to be careful not to scrape the conductors because if you do, it will expose the Aluminium core which oxidises to a black mess when it comes in contact with activated Flux. Having said that, I have managed succesfully to solder CCA by carefully stripping the insulation and soldering very quickly with a good Rosin cored Solder.
As an aside, If you examine the connections from the incoming BT Cable to your Master Socket, you will probably find that the incoming Pair is crimped using "Jelly" (Gel filled) Crimps to a short pair od tail befor connection to the Master Socket A & B Terminals. I believe this to be because BT installed a lot of Aluminium cable in the 70's and 80's which corrodes very quickly when in contact with other metals and moisture.
