MOV Search

Started by ABLE1 in sci.electronics.basics1 year ago 4 replies

Hello, I am an Alarm Technician among other things or stuff. I was thinking about installing a simple MOV on the Transformer that feeds...

Hello, I am an Alarm Technician among other things or stuff. I was thinking about installing a simple MOV on the Transformer that feeds power to the Alarm Board. The industry standard is 16.5VAC 40VA plug in Transformer. 120 Volt Input. Can anyone point to a specific MOV that would serve as a good lightning or surge protection if placed across the output terminals of the transformer...


DC motor soft start

Started by Bob Engelhardt in sci.electronics.basics1 year ago 6 replies

I found this neat soft-start circuit on the eevblog forum. Its neatness is that the gate threshold voltage occurs immediately and then the RC...

I found this neat soft-start circuit on the eevblog forum. Its neatness is that the gate threshold voltage occurs immediately and then the RC softness kicks in. V+ ________________________ V+ | | 1M ___________ V- |___1u___| | | | |-- |------| |-- | V- ____________| As...


Potentiometer Project

Started by Searcher7 in sci.electronics.basics1 year ago 5 replies

I'm working on a custom project that involves potentiometers and picture adjustments on the monitor they are connected to. To determine whether...

I'm working on a custom project that involves potentiometers and picture adjustments on the monitor they are connected to. To determine whether or not the potentiometers I need exist or if I need to build them, I need to resolve two questions and the possible issues they bring up. 1) This may seem like a crazy question, but are there low-friction potentiometers? (I'm referring to the physica...


the fable of the diode

Started by RichD in sci.electronics.basics1 year ago

Once upon a time, there was a village called Diode. The inhabitants were an excitable lot, who tended to get charged easily, positively or...

Once upon a time, there was a village called Diode. The inhabitants were an excitable lot, who tended to get charged easily, positively or negatively. They liked to play musical chairs. When a negative charge shifted to a higher seat, that was a current of -1. A positive moving down, was also -1. One day, there were 5 seats, filled with negatives. But Eddie Electron, in #5, had...


DC motor supply

Started by Bob Engelhardt in sci.electronics.basics1 year ago 5 replies

I have a 24v DC motor that I'm using with a PWM controller supplied by a 24v SMPS. I want to be able to briefly switch the motor to 48v with a...

I have a 24v DC motor that I'm using with a PWM controller supplied by a 24v SMPS. I want to be able to briefly switch the motor to 48v with a relay. I don't have a 48v supply, but I do have a 24v transformer & bridge. I know that the following will give me the 48v, and I think that the Motor Control will be OK with it. But I'd like to know if I'm missing something. The relay will d...


DC relay coil

Started by Bob Engelhardt in sci.electronics.basics1 year ago 5 replies

I have a DC relay with the coil connections marked "+" & "-". Does it matter? The relay operates with either polarity so there is no internal...

I have a DC relay with the coil connections marked "+" & "-". Does it matter? The relay operates with either polarity so there is no internal flyback diode. It's a 24v, 33ma coil for those who want to know. Thanks, Bob


Semiconductor manufacturing locations

Started by Michael Darrett in sci.electronics.basics1 year ago 4 replies

Hello, In light of the cargo ship debacle in the Pacific, I am trying to determine which companies still manufacture semiconductors in the US...

Hello, In light of the cargo ship debacle in the Pacific, I am trying to determine which companies still manufacture semiconductors in the US and Europe. I found these: https://www.thomasnet.com/articles/top-suppliers/semiconductor-suppliers-manufacturers/ https://www.bisinfotech.com/top-ten-transistor-manufacturers/ Apparently Analog Devices is headquartered in the US but it's unclea...


transformer core material

Started by Tom Del Rosso in sci.electronics.basics1 year ago 29 replies

AIUI you use iron cores for low frequency and ferrite for high frequency because ferrite doesn't get magnetized, so why couldn't aluminum do the...

AIUI you use iron cores for low frequency and ferrite for high frequency because ferrite doesn't get magnetized, so why couldn't aluminum do the same? -- Defund the Thought Police


Confirmation needed

Started by Bob Engelhardt in sci.electronics.basics1 year ago 5 replies

I'm going to make a 12v DC power supply with a linear reg. I will half-wave rectify 12v AC and have a smoothing cap. The load is only...

I'm going to make a 12v DC power supply with a linear reg. I will half-wave rectify 12v AC and have a smoothing cap. The load is only 10ma. So: 12v RMS is 17v peak, minus the diode drop of 0.7 is 16.3v peak. Using a 47uF cap, the ripple will be 3.5v p-p. So the min voltage into the regulator will be 16.3-3.5 = 12.8. Ripple calculated from Vpp = i/fC (.010/(60*47e-6). Am I missing ...


Solar charger

Started by AK in sci.electronics.basics1 year ago 10 replies

I have a solar charging I am using with my car battery. The current voltage of the battery is 12.7 volts. And the charger is still...

I have a solar charging I am using with my car battery. The current voltage of the battery is 12.7 volts. And the charger is still charging. Here are some specs for the charger. Rated power output = 5W Operating power voltage = 18V Operating power current = .33A Trickle charging current = .2A Floating charging Voltage = 13.8 Overcharge Protection Voltage = 14.1 Voltage At what ...


Ask a Question to the Electronics-Related community

To significantly increase your chances of receiving answers, please make sure to:

  1. Use a meaningful title
  2. Express your question clearly and well
  3. Do not use this forum to promote your product, service or business
  4. Write in clear, grammatical, correctly-spelled language
  5. Do not post content that violates a copyright