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Digital transistor?

Started by Sylvia Else in sci.electronics.design2 years ago 13 replies

https://www.farnell.com/datasheets/2353855.pdf I bought a few of these. I don't know what is intended by "digital transistor" since the...

https://www.farnell.com/datasheets/2353855.pdf I bought a few of these. I don't know what is intended by "digital transistor" since the charge storage time defeats any attempt to use them at a high frequency, and there's no way to add a Schottky diode to prevent saturation, or a speed-up capacitor across the base resistor. I'm using this and the corresponding PNP type to do level shift...


LTspice tapped inductor

Started by Clive Arthur in sci.electronics.design1 year ago 18 replies

I have an inductor wound on some 22mm plastic pipe, so essentially air-cored. It's over 120 turns, 700mm long and uses resistance wire. It's...

I have an inductor wound on some 22mm plastic pipe, so essentially air-cored. It's over 120 turns, 700mm long and uses resistance wire. It's about 12uH. There are 30 capacitors connected evenly along the coil commoned to a copper pipe busbar. It simulates a long, peculiar transmission line. I want to LTspice it. OK, lots of small inductors with some resistance and the capacitors. ...


Question about capacitor usage

Started by Lamont Cranston in sci.electronics.design6 months ago 1 reply

I ordered what turned out to be poor quality capacitors from...Amazon. 6 of the 12 failed. The failure was increased dissipation and reduced...

I ordered what turned out to be poor quality capacitors from...Amazon. 6 of the 12 failed. The failure was increased dissipation and reduced capacitance. These are 20kV capacitors failing at about 4kV. If I had read the reviews I would have saw they fail at low voltages. I used the caps in a tripler, the caps that failed were the caps that passed all the current flow, not the filter caps ...


Antique radio

Started by Don Y in sci.electronics.design6 months ago 8 replies

I rescued a ~100 year old radio a while back (SWMBO likes to decorate with antiques and this gives me a place to hide some kit). It is tuned...

I rescued a ~100 year old radio a while back (SWMBO likes to decorate with antiques and this gives me a place to hide some kit). It is tuned with a massive "arm" that rotates a variable capacitor. The exposed end of the actuator is visible in photo 10/11 at [Not t


Short track and impedance matching

Started by Klaus Vestergaard Kragelund in sci.electronics.design7 months ago 20 replies

Hi We have a GaN FET that is dumping voltage into a capacitor. The GaN drain is connected to 50V, and the capacitor is connected on the...

Hi We have a GaN FET that is dumping voltage into a capacitor. The GaN drain is connected to 50V, and the capacitor is connected on the source of the FET. Sort of like this: https://www.infineon.com/export/sites/default/_images/product/power/GateDriver/circuit_diagram/S ingle-High-Side-Driver_Diagram.jpg_1153011823.jpg "To load" is connected to a small 50pF capacitor to ground. We n


Low Pass Filtering in Op Amps

Started by Ricky in sci.electronics.design9 months ago 2 replies

Trying to use a differential op amp with low pass filtering in the inverting configuration has always seemed limited. If the cap is across the...

Trying to use a differential op amp with low pass filtering in the inverting configuration has always seemed limited. If the cap is across the feedback resistor, at the highest frequencies it can only provide as much attenuation, as the op amp provides gain. When the feedback resistor is shorted by the capacitor, the circuit becomes a voltage follower. Not so effective as a low p


PCN Process and Notification Specification

Started by Ricky in sci.electronics.design12 months ago 2 replies

I'm being asked by a potential customer if I'm familiar with "PCN process and notification". My company does not normally make changes to...

I'm being asked by a potential customer if I'm familiar with "PCN process and notification". My company does not normally make changes to products other than to substitute components that are functionally equivalent. A different brand of resistor, or capacitor, sometimes chips, are used when the original part is not available. I don't generate a PCN for such changes. Is th


Measuring the Disspation of the self capacitance of a thru hole resistor.

Started by Lamont Cranston in sci.electronics.design1 year ago 44 replies

I have added a 10MΩ resistor across a high Q LC (on a Q meter) and did the math on the drop in Q to get the value, but instead of 10MΩ I...

I have added a 10MΩ resistor across a high Q LC (on a Q meter) and did the math on the drop in Q to get the value, but instead of 10MΩ I got 4,280,000Ω. I'm tuning out the self capacitance, but think maybe I have the loss resistance multiplied by the Q of the resistors self capacitor (9,342,398Ω) in parallel with the 10MΩ giving me the low measurement of 4,2


pad-to-pad capacitance

Started by sea moss in sci.electronics.design1 year ago 8 replies

Two part question (my google skills have failed me for both): 1. Does anyone know approximate pad-to-pad capacitance for the common SMD...

Two part question (my google skills have failed me for both): 1. Does anyone know approximate pad-to-pad capacitance for the common SMD packages (0201, 0402, 0603, 0805)? Ever measured it? I can't use the parallel plate capacitor formula, since the plates are adjacent, not parallel. (assume there is no copper below the pads) 2. Given an SMD footprint as above, how close does a g


power supply subtelties

Started by Anonymous in sci.electronics.design1 year ago 14 replies

I never thought a lot about general-purpose bench type power supplies, but now we have to design some. A power supply has two knobs (or SCPI...

I never thought a lot about general-purpose bench type power supplies, but now we have to design some. A power supply has two knobs (or SCPI commands in our case), voltage and current limit. A power supply should have low impedance at high frequencies, so after whatever current limit circuit is has, there must be a real capacitor. When you short a bench supply, you get a spark from the e...


Bob Parker's Blue ESR Meter - query

Started by Charlie+ in sci.electronics.design4 months ago 4 replies

Apart from capacitor ESR checking, I use this meter for checking and tracking battery ESRs. Can anyone give me a safe upper voltage...

Apart from capacitor ESR checking, I use this meter for checking and tracking battery ESRs. Can anyone give me a safe upper voltage level opinion for not damaging the meter in this use? I have used it to check 2S Li-ion but could you get away with a 10S (42V) battery or 48V e-bike battery for example? The meter is too useful to damage! Or perhaps a standard capacitor in series would be a ...


that weird T502 board

Started by John Larkin in sci.electronics.design2 years ago 3 replies

We finally got a batch of boards. https://www.dropbox.com/s/rul9yep9ys0snyo/T502A_PCB.jpg?raw=1 None of the board houses minded making the...

We finally got a batch of boards. https://www.dropbox.com/s/rul9yep9ys0snyo/T502A_PCB.jpg?raw=1 None of the board houses minded making the three v-score breakaways. Tiny, in this case some 50 mil high, reference designators don't seem to be a problem these days. These look ink-jet printed to me. My test capacitor is upper-right, layer 1 to the layer 2 ground plane. If the board was f...


Filter Cap for a battery pack ?

Started by Sid 03 in sci.electronics.design2 years ago 5 replies

I need to select a capacitor for a battery pack. I see a lot of circuits that use Alkaline batteries and then have a ceramic capacitor across the...

I need to select a capacitor for a battery pack. I see a lot of circuits that use Alkaline batteries and then have a ceramic capacitor across the leads of the series battery pack to act as a filter. My question is how do you size the cap ? I hate just looking at what someone else has done and just guess or copy. I have 4x 1.5v alkaline batteries in series powering a amplifier circuit. ...


LD1117 capacitor

Started by Jasen Betts in sci.electronics.design2 years ago 14 replies

The LD1117 data sheet makes no mention of what type of 10uF capacitor to use at the output. is it stable with ceramic there or does it, like...

The LD1117 data sheet makes no mention of what type of 10uF capacitor to use at the output. is it stable with ceramic there or does it, like the LM1117, need something with more ESR? -- Jasen.


txlines

Started by Anonymous in sci.electronics.design2 years ago 40 replies

Everything that conducts is a lossy transmission line. A solenoid inductor. https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 A...

Everything that conducts is a lossy transmission line. A solenoid inductor. https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 A series string of surface-mount resistors. A ground plane or power pour. A wound-foil capacitor. A wirewound resistor. A piece of wire in free air. A via. A pcb trace, of course. -- Father Brown's figure remained quite dark and ...


Turbo Royer/Baxandall in boost configuration

Started by bitrex in sci.electronics.design2 years ago 62 replies

Is it possible to take your standard Baxandall and tap the capacitor, take an aux winding off the secondary and feed a somewhat higher DC...

Is it possible to take your standard Baxandall and tap the capacitor, take an aux winding off the secondary and feed a somewhat higher DC voltage to the cap (through the usual two-diode supply handoff arrangement), and use it to feed the gate drive to the transistors as well, which would be clocked rather than self-oscillating. The goal would be to have a quiet step-up converter that co...


Fun with accelerators

Started by Anonymous in sci.electronics.design2 years ago 32 replies

These guys get to play with stored energy in a different way than we did back when one would have a class mate toss you a charged up capacitor...

These guys get to play with stored energy in a different way than we did back when one would have a class mate toss you a charged up capacitor for shits and giggles. https://www.youtube.com/watch?v=xlzIUKyA1eQ


Emitter Couple Latch

Started by Piglet in sci.electronics.design2 years ago 2 replies

Here is a very simple circuit that must have been done before but I don't recall ever seeing published. I call it an emitter coupled latch. I...

Here is a very simple circuit that must have been done before but I don't recall ever seeing published. I call it an emitter coupled latch. I guess it's an emitter coupled schmitt trigger taken to extreme. The lower sketch shows how I used it in an inrush limiter to monitor when a big supply capacitor gets charge


Wetting current

Started by Klaus Vestergaard Kragelund in sci.electronics.design2 years ago 59 replies

Hi I am working on a design where we are monitoring a relay, if it has been energized. That is done with high ohmic resistor and a source...

Hi I am working on a design where we are monitoring a relay, if it has been energized. That is done with high ohmic resistor and a source voltage, detecting a current when drawn But, contact wetting could be a problem, so have added a small capacitor on the contacts, so when they are closed a relatively high current runs for a short period of time to punch through the oxide layer of ...


How to read this color code.

Started by none in sci.electronics.design3 years ago 3 replies

I have this capacitor in a rectangular package with two rows of three dots: black brown green yellow gold brown The other side reads...

I have this capacitor in a rectangular package with two rows of three dots: black brown green yellow gold brown The other side reads EL-MENCO upside down, so the dots may be upside down. The paint is in a recess, where all but the the first two (black brown) are circular. Those are a circle with a point to the right. How must those color codes been read? It always helps if...