Why are computer power supplies like this?

Started by Anonymous in sci.electronics.basics1 week ago 12 replies

I noticed this before and again last night. I am changing plugs from a bad supply to a good one. There is a connector with 20 or so wires that...

I noticed this before and again last night. I am changing plugs from a bad supply to a good one. There is a connector with 20 or so wires that plugs into the motherboard. 6 different color wires. But all the wire of a poarticular color go to the same trace on the power supply circuit board. So all the reds to one trace, all the yellows to another trace and so on. So why all the different wire...


Dielectric Grease

Started by Bret Cahill in sci.electronics.basics1 week ago 18 replies

I had a poorly soldered wire acting up. I smeared some Permatex tune up grease on it and it solved the problem. It doesn't seem to be a good...

I had a poorly soldered wire acting up. I smeared some Permatex tune up grease on it and it solved the problem. It doesn't seem to be a good conductor except when 2 metal contacts coated with it actually touch, then the resistance drops noticeably as compared to the dry electrodes. Bret Cahill


It's hard to filter a spike,

Started by George Herold in sci.electronics.basics2 weeks ago 8 replies

This comes out of my weird 60 Hz pickup thread on sed. It seems like a basic thing, hence SEB. I've got a Fet gate drive that couples, via a...

This comes out of my weird 60 Hz pickup thread on sed. It seems like a basic thing, hence SEB. I've got a Fet gate drive that couples, via a common cable into a signal line. (C_couple ~= 10-100pF, the source impedance drivibng the signal line is kinda high ~2k ohm. A fast switching spike on the gate makes a pulse on my signal. As I try to filter it out... say by slowing down the switc...


will this work

Started by default in sci.electronics.basics2 weeks ago 12 replies

What I want to do is make a 12vdc electronic circuit breaker, with essentially no voltage drop for current sensing. A 12 Volt relay will carry...

What I want to do is make a 12vdc electronic circuit breaker, with essentially no voltage drop for current sensing. A 12 Volt relay will carry current on it's normally open pins until the circuit trips. The question: can I run an op amp (or comparator) with a single supply (the same 12V I'm monitoring) AND make use of the high voltage gain of the amp to sense the voltage drop in the wi...


Open the (mosfet) gate!

Started by Anonymous in sci.electronics.basics2 weeks ago 55 replies

I was looking at this datasheet: http://www.irf.com/product-info/datasheets/data/irlz34n.pdf Rds,on is 0.035 ohm with Vgs=10V (Id=16A) and...

I was looking at this datasheet: http://www.irf.com/product-info/datasheets/data/irlz34n.pdf Rds,on is 0.035 ohm with Vgs=10V (Id=16A) and it's advertised as such on the first page. But at Vgs=5V (Id=16A) the Rds,on is 0.046 ohm! I thought it was a logic level mosfet; I thought the gate would be FULLY OPEN at 5V... I guess I was wrong..? Michael


Deformables Hack For Melted Large Screen TV

Started by Bret Cahill in sci.electronics.basics2 weeks ago 5 replies

An acquaintance said her TV didn't work. I knew the problem immediately: Everything including asbestos cement warps from the heat in the valley,...

An acquaintance said her TV didn't work. I knew the problem immediately: Everything including asbestos cement warps from the heat in the valley, not just mother boards. I applied about a half dozen different bending moments to the monster with my bare hands, and, sure enough, except for some white noise on the left side, got it to work. The Fonz would be envious. A bungee cord / 2X4...


cutting metal

Started by RichD in sci.electronics.basics3 weeks ago 35 replies

Doing a home project, I need to cut some aluminum. It's a strip 1/20" thick, 2" wide. I have to cut it in two, that is, a straight 2"...

Doing a home project, I need to cut some aluminum. It's a strip 1/20" thick, 2" wide. I have to cut it in two, that is, a straight 2" cut. Should I seek a specialized handsaw for this job? Or a bolt cutter, or some such. Suggestions? I have minimal metal shop experience, but figure in a group of engineers, there ought to be a few metal benders - -- Rich


Might Be Stupid, But I Want Soe Opinions

Started by Anonymous in sci.electronics.basics3 weeks ago 49 replies

Got this camera, runs on two AA batteries. I want to eliminate them. I do not want USB, I want to have a three volt walwart, or one that is...

Got this camera, runs on two AA batteries. I want to eliminate them. I do not want USB, I want to have a three volt walwart, or one that is regulated down to three volts. I am not willing take the camera apart but I am willing to modify the cap for the batteries which is also the cap for the SD card it takes. I know I will probably have to eliminate the shorting bar which puts th


Electrify the fence; problem solved?

Started by Anonymous in sci.electronics.basics3 weeks ago 4 replies

http://www.msn.com/en-us/news/world/woman-dies-after-jet-engine-air-blast/ar-BBEkmRB

http://www.msn.com/en-us/news/world/woman-dies-after-jet-engine-air-blast/ar-BBEkmRB


A timer device with relay

Started by Test in sci.electronics.basics3 weeks ago 11 replies

I've been looking for a low power and low cost timer device or info on how I could use to build one. I need to turn a relay on on a 5V device (a...

I've been looking for a low power and low cost timer device or info on how I could use to build one. I need to turn a relay on on a 5V device (a weather meter doing a number of other task as well). The weather meter uses too much amps for it to run on a battery. The low poer timer device would run on coin cell batteries and very hour or another predetermined time turn on a relay which would t...


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