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. ...

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...

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...

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...

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

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

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

Struggling to meet strict USB current-draw rules. Some of the problems start with small TI buck and boost converters that use the Peak...

Struggling to meet strict USB current-draw rules. Some of the problems start with small TI buck and boost converters that use the Peak Current Control method, with the input current always ramping up to a high maximum value. Multiple converters run from the supply, and capacitors C1 C2 = 100uF try to average the current to under 500mA. Schematic: https://www.dropbox.com/s/mol...

Tariel Kapanadze[1], has invented a multi kilowatt free energy generator. Several different implementations are shown[2][3][4] In one such...

Tariel Kapanadze[1], has invented a multi kilowatt free energy generator. Several different implementations are shown[2][3][4] In one such contraption the components include a radiator buried in the ground, a wire to a water pipe, a Tesla coil/joule thief, a spark gap, transformer, capacitors, 5 ferrite cores from old TV HV transformers, and some other unidentified components.[4] On July...

I've just built up a batch of PCBs with several LM317 and LM337 regulators on them. As this thing will be in a hot environment, I wanted to...

I've just built up a batch of PCBs with several LM317 and LM337 regulators on them. As this thing will be in a hot environment, I wanted to avoid electrolytics so I used 10uF MLCC ceramic capacitors on the inputs and outputs of the regulators. Now that I have built it, all of the regulators oscillate! I had thought that it was only LDOs (with the drain or collector of the pass device ...

Hi For an application I need to protect the electronics of an RS485 interface from surges (8/20us 1kV pulse) The normal way be to use a...

Hi For an application I need to protect the electronics of an RS485 interface from surges (8/20us 1kV pulse) The normal way be to use a transzorb, in a SMA housing or even a SOT23 device. That is not possible since we have to be able to withstand up to 30V DC on the bus also (that is handled by a special RS485 IC) The problem is that the selected breakdown voltage of the transzorb ...

For most of my projects I use either a 14.7456 MHz crystal (57600*256) = or=20 20.000 MHz (for USB 96 MHz 24*f/5). The 20 MHz crystal I am using...

For most of my projects I use either a 14.7456 MHz crystal (57600*256) = or=20 20.000 MHz (for USB 96 MHz 24*f/5). The 20 MHz crystal I am using = specifies=20 a 20 pF parallel load, but my boards have 12 pF capacitors. I just = noticed=20 this and I think the value had been selected for a previous brand of=20 crystal, but the oscillator frequencies measure pretty close to the = ideal=20 ...

I have this circuit driving a pulsed laser. I want to compute the energy dumped into the laser and the energy stored in the power...

I have this circuit driving a pulsed laser. I want to compute the energy dumped into the laser and the energy stored in the power supply capacitors. The ballpark is 120 amps into a 20 volt laser for a few hundred microseconds. What I did was create a "B" behavioral current source whose equation is I = V(LASER) * I(LASER) which represents power, and dump that into a 1 farad cap. The...

Speaking of high reliability... I think that it is often a somewhat neglected issue, so I start this thread as a mean to collect *practical*...

Speaking of high reliability... I think that it is often a somewhat neglected issue, so I start this thread as a mean to collect *practical* observations for people who care about long MTBF. In other words, "if I had to build a device which should last 50 years, I would... what?" Resistors (if not overloaded): immortal Ceramic capacitors: as above Tantalum/nobium caps: ? Electrolytic...

LM317's like some ESR in their output capacitors. I don't want any electrolytic or tantalum caps in my new thing, just ceramics, and the sim...

LM317's like some ESR in their output capacitors. I don't want any electrolytic or tantalum caps in my new thing, just ceramics, and the sim sure rings: https://www.dropbox.com/s/11b3w42nsvpliki/317_nocomp.jpg?raw=1 But this fixes it: https://www.dropbox.com/s/9q80heyfbwh5frp/317_comp.jpg?raw=1 This ain't rocket science, but I haven't seen it done before. -- John Larkin ...

I have never known what the electrolyte is made from, inside of electrolytic capacitors. Is it a water based material, or oil based? If its...

I have never known what the electrolyte is made from, inside of electrolytic capacitors. Is it a water based material, or oil based? If its water based, it will likely freeze if left outdoors in cold weather. For example, your car radio has caps, and if it's parked outdoors in the winter, the caps in it will freeze. Yet, I have never found my car radio working poorly in cold weather. This ma...

I have been designing (using)various Linear tech power supply chips. It seems current mode is the way to go. You can use their simulation tools....

I have been designing (using)various Linear tech power supply chips. It seems current mode is the way to go. You can use their simulation tools. It seems that the whole control of the whole power supply boils down to one external pin with two capacitors and a resistor that you attach to it. You pretty much start off with what their data sheet gives you , then use their simulatio

I'm tidying up my home lab and getting back into it after a lapse of several years. I have unused electrolytic capacitors going back anywhere...

I'm tidying up my home lab and getting back into it after a lapse of several years. I have unused electrolytic capacitors going back anywhere from 10 to 30 years, stored in air conditioning. I understand that electrolytics can't be sold as new if they are more than 2 or 3 years old. At what age do they become unreliable and unsuitable for breadboarding and repair? I understand repair is th...

I have set up simple circuit to test breakdown voltage: transformer + voltage doubler (with 22uF filterging capacitors) delivers about 156V. ...

I have set up simple circuit to test breakdown voltage: transformer + voltage doubler (with 22uF filterging capacitors) delivers about 156V. 156V goes trough 2.2M resistor to part under test. Paralel to the part is voltmeter. This seems to give reasonable results on most parts. However on some mosfets I see curious fenomenon: reading on voltmeter slowly increase and then stabilize at high...

Hello, Experts I would like to ask for your opinion on following issue in RF PCB layout. I am dealing with a layout of RF PCB. There are...

Hello, Experts I would like to ask for your opinion on following issue in RF PCB layout. I am dealing with a layout of RF PCB. There are different components in the schematic, all are in SMT packages - fully internally matched to 50 Ohm amplifiers, bias-T, AC coupling 0402 capacitors, fixed attenuators, programmable attenuators, filters, RF switches. All components are declared in their