Inductance calculations

Started by Peter Percival in sci.electronics.basics13 hours ago 5 replies

Somewhere there must be a formula for the inductance of a hand-wound coil. Air core, one layer of wire (of given swg) close-wound, diameter of...

Somewhere there must be a formula for the inductance of a hand-wound coil. Air core, one layer of wire (of given swg) close-wound, diameter of former (cardboard, probably inside of toilet paper roll), length of coil,... (what else?), therefore inductance equals ...


Two diode vs four diode rectification

Started by Peter Percival in sci.electronics.basics2 days ago 31 replies

What is the advantage of a four diode bridge full-wave rectifier over a two diode full-wave rectifier. There must be some, else why accept the...

What is the advantage of a four diode bridge full-wave rectifier over a two diode full-wave rectifier. There must be some, else why accept the extra cost? -- "He who will not reason is a bigot; he who cannot is a fool; he who dares not is a slave." - Sir William Drummond


Harmon divider 10:1 and 100:1

Started by amdx in sci.electronics.basics3 days ago

Just found this neat method to make 10:1 voltage dividers. Not as important now that you can get such precision resistors, but with this you...

Just found this neat method to make 10:1 voltage dividers. Not as important now that you can get such precision resistors, but with this you don't need them. Also measurable on a single voltage range so no worry about another attenuator in your meter. Again not so important with modern meters. I had to read it twice to understand it, maybe you will do better. > http://conradhoffman.co


12 Vdc led running hot

Started by AK in sci.electronics.basics6 days ago 10 replies

I bought some 12 VDC 5 mm red leds. They work find but... when I touch the wires going into the led, they were hot enough that I had to...

I bought some 12 VDC 5 mm red leds. They work find but... when I touch the wires going into the led, they were hot enough that I had to remove my hand. That does not seem normal. Thanks.


Anyone with plc experience?

Started by default in sci.electronics.basics1 week ago 3 replies

I was looking for a ready made timer for a hydroponic system I'm tinkering with and came across some el-cheapo PLCs on Amazon, and figured this...

I was looking for a ready made timer for a hydroponic system I'm tinkering with and came across some el-cheapo PLCs on Amazon, and figured this would work lots better than a timer that would need a lot of additional circuitry to adapt. The catch is that they mention a programming software that is from Mitsubishi and costs $500+ . After looking around I found some cheaper alternatives but ...


GFCI/lightening

Started by default in sci.electronics.basics1 week ago

I had a lightning strike hit an antenna mast and it took out a lot of electronics in my house. It actually popped circuit breakers in the house...

I had a lightning strike hit an antenna mast and it took out a lot of electronics in my house. It actually popped circuit breakers in the house along with taking out the TV, modem, KVR switch, low voltage LED lighting, and several power supplies. The interesting thing was the circuit for the Ground Fault outlet that feeds my outdoor workbench was kaput, but didn't show any signs of being ...


Current vs. wire gauge

Started by Peter Percival in sci.electronics.basics1 week ago 7 replies

What current can 18AWG wire carry? And, more usefully, is there a table somewhere giving this info for all the usual gauges?

What current can 18AWG wire carry? And, more usefully, is there a table somewhere giving this info for all the usual gauges?


The Tardigrades

Started by Banders in sci.electronics.basics2 weeks ago 1 reply

We can't just leave them there to die.

We can't just leave them there to die.


Rebuild computer speakers

Started by AK in sci.electronics.basics2 weeks ago 2 replies

I bought some Inland Pro Sound 2000 speakers from a thrift store. It is an amplified system putting out about 7 watts. They sound pretty...

I bought some Inland Pro Sound 2000 speakers from a thrift store. It is an amplified system putting out about 7 watts. They sound pretty poor. I remember making my own 8 ohm speakers years ago using a woofer, midrange, tweeter, and a cross-over network. Can I do that also with this system? Thanks.


Teaching Transistor Theory

Started by Cursitor Doom in sci.electronics.basics3 weeks ago 19 replies

I've just had a pedagogic revelation! Here it is: Transistor theory is much more effectively taught if explained as a *discovery* (which it...

I've just had a pedagogic revelation! Here it is: Transistor theory is much more effectively taught if explained as a *discovery* (which it was) than as an invention (which it never was). All these decades I've been wrestling with this conundrum and all it took to clear things up was a handful of these amazing mushrooms. Yay! :-D Okay, I was joking. But seriously, think about it. The co...


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