.model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65 Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS) That's in the standard library....

.model SMCJ33A D(Ron=.4 Roff=8Meg Vfwd=.7 epsilon=100m Vrev=38.65 Vpk=33 revepsilon=4 mfg=Littlefuse type=TVS) That's in the standard library. It behaves like a symmetric zener. Why? Does "type" do that? There are unipolar TVS diodes, too.

LEDs and lasers get way more efficient when they are cold. But their junction drop increases too. So it seems that driving them from...

LEDs and lasers get way more efficient when they are cold. But their junction drop increases too. So it seems that driving them from some magical Thevenin source would temperature compensate the light output. Has anyone done this? I need to hold some dBm level from a laser source from -40 to +85C and that might be a simple way to do it.

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...

> Anyone know of any ICs designed for measureing distances with RF? I'm thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one...

> Anyone know of any ICs designed for measureing distances with RF? I'm thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one foot. The basic method of one device emitting a signal and another echoeing it back would be attractive. > Any recommendations? > > Hul Dunno about ic's, but I would look at 10 GHz gunn diode intruder alarm modules as a starting point.

leads to this one... https://www.dropbox.com/s/cgaxalnn3hhf315/RRIO_Logamp.jpg?raw=1 where we use the substrate diode of a RRIO opamp as a...

leads to this one... https://www.dropbox.com/s/cgaxalnn3hhf315/RRIO_Logamp.jpg?raw=1 where we use the substrate diode of a RRIO opamp as a logarithmic current-to-voltage converter. There are better ways to do this, but maybe none so cute. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable whe...

There used to be a bunch of low-barrier schottky diodes with Cjo < < 1 pF and equivalent series resistance < 5 ohms, SC79...

There used to be a bunch of low-barrier schottky diodes with Cjo < < 1 pF and equivalent series resistance < 5 ohms, SC79 package. BAT63 SMS1546 SMS3927 but they seem to be all gone. Strange. SMS3922 is available, with C=0.7 pF and Rs = 9 typ. Maybe I can use a small phemt as a diode. It seems as if quantity-billion ICs keep killing off fast discrete parts. -- If a man wil

I'm using a TIP31C (pnp in to-220 pac) as a temp sensor (diode connected) There's a couple of depletion fets in series as current limiters....

I'm using a TIP31C (pnp in to-220 pac) as a temp sensor (diode connected) There's a couple of depletion fets in series as current limiters. (LND150) The b-e junction starts to zener at ~30 V (only two tested so far). So I've got ~1.5 mA flowing at 30 V. Is this going to damage the junction? Will it take time? I'm going to measure forward voltage again after zenering for 15 minutes. Sho...

LTspice is a nice program... well, it's ok in many respects and great in others. But it can be a PITA to find models for. I'm looking at a...

LTspice is a nice program... well, it's ok in many respects and great in others. But it can be a PITA to find models for. I'm looking at a number of possible parts to use in a new design but many of them have no spice models. I'm not so worried about finding an accurate LED model. But I'm using a Schottky diode to prevent back feeding of power through a regulator and I need a

I'm still iterating on my high-voltage pulse generator. Rev C looks very good. I've been pushing it up voltage and frequency (like,...

I'm still iterating on my high-voltage pulse generator. Rev C looks very good. I've been pushing it up voltage and frequency (like, 1200 volts and 4 MHz) and seeing what parts fry, and working on them. I have a dpak schottky diode in a sort of snubber place. According to Spice, it shouldn't get too hot, and it's soldered to all sorts of copper pours and thermal vias and stuff. It's an S...

Hello, I want is there anyone that has used a BJT instead of ultra low leakage diode(

Hello, I want is there anyone that has used a BJT instead of ultra low leakage diode(

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...

Folks, Got a Silicon Labs 8051Fxxx with 5V-tolerant ports. In the abs max it says 5.8V is the limit. Well, if one uses the typical diode...

Folks, Got a Silicon Labs 8051Fxxx with 5V-tolerant ports. In the abs max it says 5.8V is the limit. Well, if one uses the typical diode against the 5V rail it could go slightly above 6V in case of a really big jolt. Since this 8051 does not have a 5V supply but just VDD (which hangs on 3.3V in this case) there can't be any parasitic substrate diodes dumping into a rail. Does anyone kno...

This is an idea for an experiment I may or may not do. The background: There have been reported seasonal variations in radioactive decay in the...

This is an idea for an experiment I may or may not do. The background: There have been reported seasonal variations in radioactive decay in the past. Now If I took a simple tritium light, and a good quality photo-diode, put both in a light proof box, and logged that with a 10 bit PIC ADC with a decent Vref for say a year to FLASH, say 1 sample / hour, run the whole thing of some battery. ...

I have a couple of simple 555 monostables, the first to delay the triggering of the...

I have a couple of simple 555 monostables, the first to delay the triggering of the second. https://www.dropbox.com/s/6uboy3fgd0ixhxa/GenerateNegPulse-1.jpg?raw=1 But I'm struggling to extract the brief -ve pulse required for the Main mono. I thought it would prove simple. But bread-boarding various combinations of R, C, diode and NPN or PNP transistor has so far not yielded a winning comb...

Sometimes one needs to power a circuit from one source or another. Most LDOs, or indeed most normal regs, feed current back up to the source....

Sometimes one needs to power a circuit from one source or another. Most LDOs, or indeed most normal regs, feed current back up to the source. LDOs tend to use a PMOS pass transistor which has a parasitic diode. I am doing a design where I am using the Ricoh R1191 for this https://eu.mouser.com/ProductDetail/Ricoh-Electronic-Devices-Company/R1191N033B-TR-FE?qs=%2Fha2p yFaduhEV6ZG3xOqbaXpS

I want to inject a 100 ps test pulse into a 50 ohm transmission line, tee-wise, sometimes, from a 25 ohm source. So I need a series...

I want to inject a 100 ps test pulse into a 50 ohm transmission line, tee-wise, sometimes, from a 25 ohm source. So I need a series switch. I'd never paid much attention to PIN diodes... they are RF stuff. But this one is shocking: https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf 2 ohms on, 0.14 pF off. And that's packaged. Chip and beam-lead parts are even bette...

Is horrible. I'm just debugging a nice diode laser controller for one customer and getting ready to do another one for another (much better)...

Is horrible. I'm just debugging a nice diode laser controller for one customer and getting ready to do another one for another (much better) customer. It uses a ZXTP25020 PNP with a biggish degeneration resistor and two-pole bypassing of the base to get low noise at high frequency. Turns out the 1/f noise is atrocious. The total noise from 2 Hz on up is only a couple of PPM, but it sho...

Got some BF245-C N channel JFETS from ebay. Wanted a quick check to see if these were actually FETS... Multimter on diode range, plus on...

Got some BF245-C N channel JFETS from ebay. Wanted a quick check to see if these were actually FETS... Multimter on diode range, plus on drain, - on source. The way I usually test these is apply some voltage to the gate to see if they conduct / do not conduct (wet finger). But in my other hand (one hand the 2 probes on the FET) I had the plastic bag with the rest of the FETS, it detects ...

Hi guys! Long time no smell.* I miss you guys, but I've been doing almost zero electronics. (I lurk every now and then) So my son wants a...

Hi guys! Long time no smell.* I miss you guys, but I've been doing almost zero electronics. (I lurk every now and then) So my son wants a cheapish DMM for Xmas. What brand should I look at? Extech? Searching this Klein tool one looks nice. Klein Tools MM400 Multimeter, Digital Auto Ranging, AC/DC Voltage, Current, Capacitance, Frequency, Duty-Cycle, Diode, Continuity, Temp 600V ~$50 on a...

https://www.dropbox.com/sh/tgu2ozch3rbgglk/AABI3U3_iexb69UHWoRIzm-Ma?dl=0 Interesting. The high junction drops might be the SiGe, or just...

https://www.dropbox.com/sh/tgu2ozch3rbgglk/AABI3U3_iexb69UHWoRIzm-Ma?dl=0 Interesting. The high junction drops might be the SiGe, or just the tiny junction size. It would make a decent 0.3 pF 13 volt diode. I might make an oscillator and evaluate phase noise/jitter. An x-ray would be cool. We need a high-res xray machine. -- If a man will begin with certainties, he shall e...