Transformerless power supply

Started by amdx in sci.electronics.basics24 hours ago 7 replies

Is it reasonable/possible to build an 8 amp 20 V transformerless power supply from a 120Vac line. I calculate about 180uf plus or minus...

Is it reasonable/possible to build an 8 amp 20 V transformerless power supply from a 120Vac line. I calculate about 180uf plus or minus depending on other components. Maybe 9- 20uf caps in parallel? I'd like to build it into a leaf blower. All plastic, absolutely no metal exposed. I think I've answered my question, I have 12, X rated caps in my junk box, but they are only 1uf....


Error of % + digits?

Started by Commander Kinsey in sci.electronics.basics1 day ago 48 replies

I just bought an amp clamp meter, and it states the error is "+/- 1.9% + 3 digits". What does the "3 digits" part mean?

I just bought an amp clamp meter, and it states the error is "+/- 1.9% + 3 digits". What does the "3 digits" part mean?


Solder these 2 wires while being able to slip the shrink tubing over the soldered connection

Started by AK in sci.electronics.basics4 days ago 6 replies

I would like to learn how to solder these 2 wires while being able to slip the shrink tubing over the soldered...

I would like to learn how to solder these 2 wires while being able to slip the shrink tubing over the soldered connection. Thanks. https://imgur.com/a/9z3z294


Turn on Dynamic Range Compression

Started by AK in sci.electronics.basics3 weeks ago 3 replies

I am trying to turn on Dynamic Range Compression or D.COMP as Denon calls it. I got up to and finished step 5. But instead of going to step 6,...

I am trying to turn on Dynamic Range Compression or D.COMP as Denon calls it. I got up to and finished step 5. But instead of going to step 6, it went to step 8, Default Y/N. Step 6 is where you can turn on Dynamic Range Compression. I want to set Comp because of the tremendous dynamic range of movie soundtracks. Here are pictures of 2 pages of the manual. https://imgur.com/a/8tWUQv...


All Ob A Sudden, Starter Motors Is So Small & Light You Can Carry 'em Home In A Filmy Shoppin Bag

Started by Bret Cahill in sci.electronics.basics3 weeks ago 5 replies

Summin didn't look right. The replacement starter motor was 2/3rds the dia of the original, mebbe haf the wait. I tink, WTF? Weren't all them...

Summin didn't look right. The replacement starter motor was 2/3rds the dia of the original, mebbe haf the wait. I tink, WTF? Weren't all them optimum nummers well settled back in the early Nicolacene? I toght, heck, no need to strap it onto the bike rack. I'll just stick hit into a shoppin bag. Affer an easy installation, the thang _akutually werked._! Affer about 2 days a theory he...


Subwoofer help

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

I would like to add a sub-woofer to my home theater system. My system calls for speakers in the 6 -> 16 ohm range. When I searched Ebay, I...

I would like to add a sub-woofer to my home theater system. My system calls for speakers in the 6 -> 16 ohm range. When I searched Ebay, I found some speakers, but found out that they need a crossover. My system has an output for a subwoofer. Could someone show me a link to something for sale or else the specs I need to look for? Thanks, Andy


Splattering solder into eye?

Started by Peter Hucker in sci.electronics.basics3 weeks ago 48 replies

Has anyone ever actually been unlucky enough to get solder splattering into their eye? I've had it hit my leg, hand, and face, but never in my...

Has anyone ever actually been unlucky enough to get solder splattering into their eye? I've had it hit my leg, hand, and face, but never in my eye. How bad is it? -- http://www.petersparrots.com http://www.insanevideoclips.com http://www.petersphotos.com Confuscious say: "War doesn't determine who's right. War determines who's left."


Diagnosing speakers

Started by Andy in sci.electronics.basics3 weeks ago 16 replies

I have a 6 speaker home theater system. However the middle 2 speakers have no sound. I checked the voltages. 0 volts when a movie is...

I have a 6 speaker home theater system. However the middle 2 speakers have no sound. I checked the voltages. 0 volts when a movie is playing versus .22 Vdc when movie is not playing. Does that help at all? Thanks, Andy


Power in use indicator please ?

Started by Steve Wolf in sci.electronics.basics3 weeks ago 50 replies

I have a water pump in a remote location. Sometimes the pump (120 volts) line springs a leak and then runs all the time with the potential of...

I have a water pump in a remote location. Sometimes the pump (120 volts) line springs a leak and then runs all the time with the potential of burning out pump. I want to build a little circuit that will tell me in my house if it is running. I have in the past build and induction coil out of a transformer and then used an LED to light up when the pump is on. I cut out one of the side


Solar Charging Night Light not working

Started by Alberto in sci.electronics.basics4 weeks ago 24 replies

Hi all, I am trying to implement a very simple solar charged night garden light. Schematics is here:...

Hi all, I am trying to implement a very simple solar charged night garden light. Schematics is here: https://www.jameco.com/Jameco/workshop/JamecoFavorites/solarled.html Basically a solar panel charges a battery. When the solar panel output is low (at night), a joule thief circuit lights a led. The joule thief part works just fine, the problem is that the dark detector (2n3906 + 4.7K resis...


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