Suppress transients on old burglar alarm

Started by Terry Pinnell in sci.electronics.basics5 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.basics5 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.basics5 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...


current regulator

Started by John Larkin in sci.electronics.basics5 months ago 14 replies

https://www.diodes.com/assets/Datasheets/AL5890.pdf The block diagram shows this as a closed-loop regulator, not just some jfet sort of...

https://www.diodes.com/assets/Datasheets/AL5890.pdf The block diagram shows this as a closed-loop regulator, not just some jfet sort of thing. The high minimum voltage and unspecified capacitance/speed limits its use, but it is cute. -- John Larkin Highland Technology, Inc lunatic fringe electronics


The wiper in a variac

Started by Robert Roland in sci.electronics.basics6 months ago 7 replies

I have been thinking about the way a variac works. One thing that puzzles me, is the wiper design: If the wiper is too narrow, the output...

I have been thinking about the way a variac works. One thing that puzzles me, is the wiper design: If the wiper is too narrow, the output voltage will cut out when the wiper is between two turns of the coil. If the wiper is too wide, it will bridge two contact points, causing one turn of the transformer to be directly shorted. Although it is not a lot of voltage, it is also not a long pi...


A balanced 12AX7 based buffer

Started by Les Cargill in sci.electronics.basics6 months ago 10 replies

I'd like to "design" and implement a simple 12AX7-based buffer for musical instrument DI purposes. I'd like the output to be balanced for ... no...

I'd like to "design" and implement a simple 12AX7-based buffer for musical instrument DI purposes. I'd like the output to be balanced for ... no good reason at all beyond having balanced inputs to play with. My questions are: - Do I really need 300V for this? What's the trade here? - Is there a nice single-package, preferably switchmode power supply that does 300V and 12.6V heater, or ...


A question about relays

Started by default in sci.electronics.basics6 months ago 21 replies

I was poking around in my truck the other day and had cause to open up the starter relay. (not the solenoid, the relay that energizes...

I was poking around in my truck the other day and had cause to open up the starter relay. (not the solenoid, the relay that energizes the solenoid) I was amazed at the size of the contacts. They were under 1/8" in diameter yet the relay is rated at 40 amps. The AC clutch relay- ditto, tiny contacts. In the case of the clutch relay I know for a fact the inductive kick must be > 100 volts


Trickle charge C-type NiMh?

Started by Terry Pinnell in sci.electronics.basics6 months ago 6 replies

I have some inexpensive 220 mAH C-type Ni-Mh batteries, https://www.amazon.co.uk/gp/product/B07BJ85NNZ The equivalent 3300 mAh C-Types I bought...

I have some inexpensive 220 mAH C-type Ni-Mh batteries, https://www.amazon.co.uk/gp/product/B07BJ85NNZ The equivalent 3300 mAh C-Types I bought a couple of years ago specified charging with 330 mA for 16 hours, but these new ones have no charging data. I have three soldered together and obviously charge in series. I've been using a trickle charge of 25 mA in the circuit of my curtain contr...


Using a TO-220 heat sink

Started by Adam Funk in sci.electronics.basics6 months ago 41 replies

Hi, To attach an LM317 (for example) in the TO-220 format to the corresponding heat sink (see link below), is it useful to apply any thermal...

Hi, To attach an LM317 (for example) in the TO-220 format to the corresponding heat sink (see link below), is it useful to apply any thermal paste in addition to the flexible mat that comes with the heat sink? Thanks. -- XML combines


Anyone here know BLDC motors well? Hobby ones particularly?

Started by Anonymous in sci.electronics.basics6 months ago 5 replies

I want to use a hobby BLDC motor to power a compact high speed spindle to be used for engraving and the like. Mainly because they are so...

I want to use a hobby BLDC motor to power a compact high speed spindle to be used for engraving and the like. Mainly because they are so compact for the power and speed. I cannot find, for a price I can justify, a 24,000 to 40,000 RPM spindle that will fit in the space I want to put it. Looking at some hobby BLDC motors and then buying some to experiment with leads me to think that on...


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