three terminal volt regulator

Started by George Herold in sci.electronics.basics7 months ago 11 replies

Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac) I need a replacement. So either a 1 amp...

Hi all, Simple question. Some 1/2 amp LM7805 is obselete (TO-220 pac) I need a replacement. So either a 1 amp 7805 http://www.onsemi.com/pub/Collateral/MC7800-D.PDF or a LM340 http://www.ti.com/lit/ds/symlink/lm340.pdf Is there any (practical) difference between the two? (besides the price.) George H.


An idea that may be of some use

Started by default in sci.electronics.basics7 months ago

I needed a small light to light some steps from my deck to the ground and in a few other places. I already had a 12V system outside. For a...

I needed a small light to light some steps from my deck to the ground and in a few other places. I already had a 12V system outside. For a cheap and dirty light I took a plastic test tube (ebay/amazon) put a short section of LED strip light into it (9 leds, served with wires) then heated the open end of the TT with a heat gun, and crimped it with a sheet metal pliers to make a waterproo...


sci.electronics.basics, Would You Like To Actually Participate In A Design ?

Started by Anonymous in sci.electronics.basics7 months ago 14 replies

This is an ESR detector for caps, electrolytics mainly that cause so many of the problems in electronic equipment. This is not meant to be a lab...

This is an ESR detector for caps, electrolytics mainly that cause so many of the problems in electronic equipment. This is not meant to be a lab quality instrument, it is mew=ant to be a fast way to check alot of caps and that does find many electronic problems. Nobody in the business will really argue with that unless they work on some weird shit. One of the earlier ones was t


mosfet bias question

Started by default in sci.electronics.basics7 months ago 3 replies

I plan to use a mosfet in a dawn to dusk switching circuit with a 12V regulated power supply. In the application notes they give the...

I plan to use a mosfet in a dawn to dusk switching circuit with a 12V regulated power supply. In the application notes they give the gate source absolute maximum voltage as +/- 10V Gate to Source. (page 1) On page 6 of the same application note they show a "Gate charge test circuit." with a 12 volt battery between the gate and source with a 50 Kohm variable resistor for the current source ...


juice the movie

Started by John Larkin in sci.electronics.basics8 months ago 1 reply

http://juicethemovie.com/ Looks interesting. -- John Larkin Highland Technology, Inc lunatic fringe electronics

http://juicethemovie.com/ Looks interesting. -- John Larkin Highland Technology, Inc lunatic fringe electronics


Sanity check for a cheap DVM

Started by bob prohaska in sci.electronics.basics8 months ago 6 replies

I'd like to check an old Radio Shack DVM for accuracy around 5 volts DC. On a brand-new cr2032 coin cell it measures 3.25 volts open...

I'd like to check an old Radio Shack DVM for accuracy around 5 volts DC. On a brand-new cr2032 coin cell it measures 3.25 volts open circuit, about 3.15 volts with a 3 kohm load. That's rather high compared to http://data.energizer.com/pdfs/cr2032.pdf, which shows ~2.95 V with a 15 kohm load. I've noticed that brand-new alkaline D cells seem to measure around 1.65 volts and credited it t...


Math Challenged.

Started by Anonymous in sci.electronics.basics8 months ago 14 replies

I know I am losing it, but I want to bring it back. I have screwed up some things. Figuring out a roll of wire, I had 95 turns of about 12"...

I know I am losing it, but I want to bring it back. I have screwed up some things. Figuring out a roll of wire, I had 95 turns of about 12" diameter. I thought pi was times radius, and that is because of not using it. And then I thought there was 1,700+ feet in a box that came with 1,000 feet. I had forgotten to divide by 12 to get feet out of inches. Losing it. Someone jus


Suppress transients on old burglar alarm

Started by Terry Pinnell in sci.electronics.basics8 months ago 15 replies

My 20 year old burglar alarm control has developed a fault that I've spent the last couple of days trying to fix. Before I ditch it and...

My 20 year old burglar alarm control has developed a fault that I've spent the last couple of days trying to fix. Before I ditch it and go through the hassle of installing a new one I'm seeking help here please. Q1: An extreme longshot as I researched in 2012 but the company had long folded, but... Anyone have or know a source of the circuit diagram for the Autona 2250 Control Unit? FWI...


Capacitor Tester

Started by Anonymous in sci.electronics.basics8 months ago 30 replies

I dont have a capacitor tester. (Well a very small one on my Digital meter) I want one that is good general use. Some seem to only go to 100 or...

I dont have a capacitor tester. (Well a very small one on my Digital meter) I want one that is good general use. Some seem to only go to 100 or 200 uF. I think you really need something that goes to maybe 4000uF. I looked at some electronics I have they have for example 2200uf. I want to spend less than 100 Canadian. I have seen a few Honeytek A6013L Capacitor Tester or Klein mm1000 which s...


What size of surface-mount components is good for a beginner?

Started by Anonymous in sci.electronics.basics8 months ago 31 replies

Greetings one and all I am laying plans to start working with SMT for the first time. Would 0805 components be a suitable size for a...

Greetings one and all I am laying plans to start working with SMT for the first time. Would 0805 components be a suitable size for a beginner, or would another size be appropriate? I have been a sometimes hobbyist for a long time, since the mid 70's when I was a teenager, but until now I have never ventured beyond through hole construction, mostly due to a combination of tooling a...


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