## Scope use question

Started by in sci.electronics.basics4 months ago 10 replies

I'd like to use both traces on my scope to look at 2 voltages that are without a common reference. E.g., across R1 & across...

I'd like to use both traces on my scope to look at 2 voltages that are without a common reference. E.g., across R1 & across R3: ________R1____ | R2 ... | R3 ____|______ I know that there are isolation probes to do this (\$\$\$), but I'm wondering if there is some clever other way to do it. In my minimal experience I can't see one, but I'm hopeful that ...

## Power Calc

Started by in sci.electronics.basics4 months ago 2 replies

Okay, here's anohter dumb quesiton. Say I have a resistor across the mains power supply. Say its 10k for argeuments sake. Mains here is about...

Okay, here's anohter dumb quesiton. Say I have a resistor across the mains power supply. Say its 10k for argeuments sake. Mains here is about 115VAC. So the resistor will disspate 1.3 watts give or take by my rekoning. Now say I put a diode in series with the resistor. Does the power dispataion now halve? just curious.

## Resistors in parallel

Started by in sci.electronics.basics5 months ago 3 replies

Hi guys, I need to make up a 15k 4 Watt resistor from a selection of half Watt resistors in parallel. But the math is a bit complex for me....

Hi guys, I need to make up a 15k 4 Watt resistor from a selection of half Watt resistors in parallel. But the math is a bit complex for me. Any ideas how I could do this please? I'm relatively new to electronics. I have a ton of half watters to use so any values you come up with I shou,d have TIA Dan

## New Motor Has Much Greater Torque/Power Than Old

Started by in sci.electronics.basics5 months ago

Yet just using "throttle" [no pedal assist] doesn't seem much better. First and only theory: the torque sensor ripped apart after hundreds of...

Yet just using "throttle" [no pedal assist] doesn't seem much better. First and only theory: the torque sensor ripped apart after hundreds of miles of slip bang of the bad free wheel. I suspected this before trying the new motor or even before the old motor went out. (A lot of problems go away on their own, although not quite as high a % as health conditions.) For confirmation remov

## How to know when to change battery in multimeter

Started by in sci.electronics.basics5 months ago 3 replies

On my multimeter, the voltage readings get inaccurate over time due to battery discharge. My meters all use 9 volt batteries. How can I tell...

On my multimeter, the voltage readings get inaccurate over time due to battery discharge. My meters all use 9 volt batteries. How can I tell when to change out the batteries? Thanks.

## Splattering solder into eye?

Started by in sci.electronics.basics5 months ago 57 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."

## Testing small Transformer questions

Started by in sci.electronics.basics7 months ago 8 replies

I have a dead Ac/Dc adaptor. I'm busted it just to learns stuff. Im trying to learn how to test Transformers. This transformer says on it...

I have a dead Ac/Dc adaptor. I'm busted it just to learns stuff. Im trying to learn how to test Transformers. This transformer says on it AM= S10405 RG 1320F. I provide this to give all information, however Im not sur= e it matters much to my question. I have so far removed from what I can gather are the Primary wires from the= board. I assume they are because they are white and black and ...

## Altering PCBs

Started by in sci.electronics.basics8 months ago

No way to pull over a heavy commercial vehicle after knocking off its tail light even if you wanted to so even though it must represent a small...

No way to pull over a heavy commercial vehicle after knocking off its tail light even if you wanted to so even though it must represent a small fraction of unreported minor accidents, freeways are littered with perfectly functional tail lights. The question is, what is the easiest way to convert the 3s X 8p 12v wiring of the LEDs to 8s X 3p? And do I really need a resistor in each series? ...

## Email configuration for security camera

Started by in sci.electronics.basics8 months ago 3 replies

I was not sure which group to post this too, so this is the closest I could find. I have a security camera sold by Harbor Freight. It is a...

I was not sure which group to post this too, so this is the closest I could find. I have a security camera sold by Harbor Freight. It is a Cobra CCTV. This is what I am trying to set up for sending me video of my camera/ https://imgur.com/a/P1R0E9P I am trying to get it set up so it will send video to my email address. I contacted Harbor Freight and there were of no help. Is t...

## Capacitor rules

Started by in sci.electronics.basics9 months ago 5 replies

Hi folks I'm really new with electronics. Doing a massive project for a retro computer system and, as a prong of this project I'm attempting...

Hi folks I'm really new with electronics. Doing a massive project for a retro computer system and, as a prong of this project I'm attempting to locate a modern equivalent of the board components. Enter the tantalum capacitor. Having gone to digikey, mouser, and newark none of them seem to have the item I'm looking for in stock. What are the rules about alternate values? The tantalum cap I'm...