single transistor oscillator

Started by Vivek N in sci.electronics.design9 years ago 11 replies

I tried building a single transistor LED flasher like this...

I tried building a single transistor LED flasher like this : http://cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html I didn't have the recommended 2n2222 - I tried with a BC548, 2n2369 and 2n3055 - None of them work. I'm using a trimpot set to 2 kiloohms and a 470 microfarad capacitor. Instead of a 100 ohm resistor I put 3 superbright LEDs in series. I get 1.2 v...


Running out of ideas: stability, bootstrap

Started by Gerhard Hoffmann in sci.electronics.design6 years ago 24 replies

Hi, all, we had a bank holiday here, nicely positioned close to the weekend and I took the free time to play with my multi-IF3601 low noise...

Hi, all, we had a bank holiday here, nicely positioned close to the weekend and I took the free time to play with my multi-IF3601 low noise amplifier. That was not so funny because it features a negative input impedance over most frequencies, so with a suitable inductance on the input it makes a stable oscillator. Some observations: - Zin is negative also with the feedback loop cu...


LTSpice: How do make a Schmitt oscillator run?

Started by Joerg in sci.electronics.design14 years ago 8 replies

Ok, simple circuit: Schmitt inverter, 10K resistor from output to input, 1000pF capacitor from input to ground. Vh set to about 20% of Vhigh....

Ok, simple circuit: Schmitt inverter, 10K resistor from output to input, 1000pF capacitor from input to ground. Vh set to about 20% of Vhigh. Should happily oscillate but I get the error message "Time step too small". Also there is a noted dip in voltage down to about 80%, something which should even be possible with a digital behavioral device. What gives? How can I fix that and make i...


unijunction equivalent circuit?

Started by Joseph H Allen in sci.electronics.design9 years ago 5 replies

So is there any simple circuit using conventional NPN and PNP transistors? I've seen this...

So is there any simple circuit using conventional NPN and PNP transistors? I've seen this circuit http://sub.allaboutcircuits.com/images/quiz/02139x02.png in _Sourcebook of Electronic Circuits_, but it doesn't really work- it latches but does not release when used in a relaxation oscillator. Perhaps it did work with lower gain transistors. -- /* jhallen@world.std.com AB1GO */ ...


My current mirror variation on the Baxandall Class-D oscillator - minor revisons

Started by Bill Sloman in sci.electronics.design2 years ago

I've changed the circuit a bit - essentially taking out bits that didn't add value - but I did change the Sallens and Keys filter to one with a...

I've changed the circuit a bit - essentially taking out bits that didn't add value - but I did change the Sallens and Keys filter to one with a bit of gain that gives you a maximally flat time delay with standard value components. The performance is marginally better. http://sophia-electronica.com/BillsBaxandall.html -- Bill Sloman, Sydney


PWM controllers... shopping

Started by sea moss in sci.electronics.design3 years ago 58 replies

Seems like every time I start a new power design, I waste a bunch of time looking for the ideal PWM controller. At the end of the day I'd...

Seems like every time I start a new power design, I waste a bunch of time looking for the ideal PWM controller. At the end of the day I'd really like to have the simplest IC possible to handle just the PWM function, and I provide my own error amp, gate driver, and reference externally. The ideal part would look like this: oscillator set by resistor, comparator non-inverting input,


LTspice Passing Parameters

Started by Ricky C in sci.electronics.design3 years ago

I'm attempting to construct a model for a 4060 device and the oscillator isn't working. I created a model to explore that and got it to work with...

I'm attempting to construct a model for a 4060 device and the oscillator isn't working. I created a model to explore that and got it to work with just two inverters. I had to add parasitics to the outputs before the simulator would run without time step errors. The 4060 model needs to work with a variable Vdd during the simulation, so I've used switches to create a push-pull o


9V Battery or 2 x AAA with 9V Converter

Started by Anonymous in sci.electronics.design9 years ago 34 replies

In terms of battery life, and assuming the same brand of Alkaline battery, is it more efficient to use a 9V battery or 2 AAA cells...

In terms of battery life, and assuming the same brand of Alkaline battery, is it more efficient to use a 9V battery or 2 AAA cells with something like the TL496 converter pictured here. http://www.electroschematics.com/6788/3v-to-9v-dc-converter/ If not, what is the approximate difference either way? The circuit involved is a test audio oscillator. Would be nice if they made mor...


inductor tempco

Started by John Larkin in sci.electronics.design7 years ago 66 replies

These look great, very high Q. I'm thinking about a 50 or maybe 100 MHz Colpitts oscillator PLL. http://www.coilcraft.com/1515sq.cfm I...

These look great, very high Q. I'm thinking about a 50 or maybe 100 MHz Colpitts oscillator PLL. http://www.coilcraft.com/1515sq.cfm I wonder if the thermal expansion tempco of the FR4 board will stretch the coil and change its native tempco. FR4 is variously cited as being around +5 to +17 ppm/K, which isn't bad. That might even reduce the tempco of the inductor. I also wonder how ...


some BFP640 SiGe measurements

Started by John Larkin in sci.electronics.design7 months ago 24 replies

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...


Wavetek 273

Started by Tim Wescott in sci.electronics.design11 years ago 32 replies

Anyone got any mileage, manuals, rumors, etc. of the Wavetek 273 signal generator? A customer is testing a PLL that I designed. The PLL is...

Anyone got any mileage, manuals, rumors, etc. of the Wavetek 273 signal generator? A customer is testing a PLL that I designed. The PLL is designed to go into the far sub-Hz bandwidths, and they're having trouble getting it to lock onto the 15kHz signal from a Wavetek 273. I've got it running off of a crystal oscillator divided down and made into a sine wave, and it's perking along ...


Crystal Controlled Oscillator

Started by Artist in sci.electronics.design11 months ago 53 replies

I have been tasked with designing a piezoelectric actuator driver at its resonant frequency. This is to replace an arrangement where the sine...

I have been tasked with designing a piezoelectric actuator driver at its resonant frequency. This is to replace an arrangement where the sine wave source is a function generator chip (the obsolete XR-2206) that must be individually tweaked on a unit, by unit basis, to match the crystal?s resonant frequency. The crystal is used as an actuator to vibrate a mirror used in a laser syste


3904 (again)

Started by Yzordderrex in sci.electronics.design3 years ago 11 replies

A client came to me with a battery design that isn't meeting lifetime spec. The unit is a small transmitter to track people in hospital type...

A client came to me with a battery design that isn't meeting lifetime spec. The unit is a small transmitter to track people in hospital type environments. The circuit runs off of a 3v battery. There is a 60k resistor from gpio output to the base of common emitter 3904. The collector is tied to one end of ferrite antenna. Other end is tied to 3v. 3904 is used between oscillator and the ferri...


ADCMP561 spice model

Started by John Larkin in sci.electronics.design8 years ago 1 reply

Analog Devices makes some nice PECL comparators, but the data sheets are old and iffy, and there don't seem to be any Spice models. It...

Analog Devices makes some nice PECL comparators, but the data sheets are old and iffy, and there don't seem to be any Spice models. It was raining and snowing and I couldn't go skiing, so I did a behavioral model. I plan to use one of these to make a pretty good 500 MHz oscillator, so I wanted to get it mostly right. Jim's TANH thing is a nice way to make a saturating stage. The open-emit...


GaN fet ring oscillator

Started by Anonymous in sci.electronics.design1 year ago 6 replies

https://www.dropbox.com/sh/4j35ny39w8fo343/AACp_DApeRQRaMLsvh3KMLWFa?dl=0 I think the frequency should settle down to 1/(10*Tpd) but it...

https://www.dropbox.com/sh/4j35ny39w8fo343/AACp_DApeRQRaMLsvh3KMLWFa?dl=0 I think the frequency should settle down to 1/(10*Tpd) but it doesn't. We might do some pcb footprint tests for the tiny EPC fets, and I thought a board with a lot of ring oscillators would be a good way to test for good soldering. The EPC data sheet recommends a tiny solder-mask-defined pad arrangement that th...


pretty good frequency counter

Started by Anonymous in sci.electronics.design3 years ago 27 replies

Anybody have one of...

Anybody have one of these? https://www.digikey.com/products/en/test-and-measurement/equipment-specialty/618?k=&pkeyword=&sv =0&pv335=349388&sf=0&FV=-8%7C618&quantity=&ColumnSort=0&page=1&pageSize=25 I'll have my new 150 MHz Colpitts LC oscillator test board in a week or so, and I need a modestly good frequency counter for testing. We usually buy some high-end Keysight counter/timer for


Precison sapphire oscillator

Started by Anthony William Sloman in sci.electronics.design1 year ago 16 replies

A recent copy of the IEEE Spectrum included this...

A recent copy of the IEEE Spectrum included this article https://spectrum.ieee.org/for-precision-the-sapphire-clock-outshines-even-the-best-atomic-clocks It isn't as stable as an atomic clock over an extended period but it's short-term accuracy is much better. Each clock period is much closer to being perfectly equal to the last one. And it is an Australian development ... -- Bill


A current mirror variation on the Baxandall Class-D oscillator for producing a reasonable clean sine wave.

Started by Bill Sloman in sci.electronics.design2 years ago 8 replies

I've up-dated my website to add a circuit diagram, some comment on it, and the text from the corresponding LTSpice .asc...

I've up-dated my website to add a circuit diagram, some comment on it, and the text from the corresponding LTSpice .asc file. http://sophia-electronica.com/BillsBaxandall.html The circuit produces a balanced pair of 1V rms 17kHz sine waves. The LTSpice simulation suggests the third harmonic content is about 60db below the fundamental, and the fifth harmonic is even smaller. It's not a par...


Trying to identify SMD with label scrubbed off - PWM, inverter, 100W 12VDC to 120VAC modified sine wave

Started by John Robertson in sci.electronics.design1 year ago 35 replies

I have a trick on-topic question, looking for possibilities for candidates for a 16-pin SMD device that has these pin outs identified so...

I have a trick on-topic question, looking for possibilities for candidates for a 16-pin SMD device that has these pin outs identified so far: 1 & 16 - RC oscillator 4 - ground 7 & 8 - drivers for a "H" style MOSFet set of four transistors that between them generate a modified sine wave running at 60Hz and 120V. So it is NOT a TI SG3524/3525 chip. The MOSFets generate the pow...


A simple tunable crystal oscillator

Started by Jan Panteltje in sci.electronics.design10 years ago 37 replies

I am going to use the 10MHz output of the Rubbitin frequency reference to make 50.000000000 MHz for my FPGA board. The plot is a bit...

I am going to use the 10MHz output of the Rubbitin frequency reference to make 50.000000000 MHz for my FPGA board. The plot is a bit complicated, and is planned like this: 25 MHz crystal > - FPGA board Spartan2 -> x2 DLL (delay locked loop that is a build in thing in the Spartan2 FPGA) -> 50 MHz -> divide by 5 in FPGA -> 10 MHz -> xor with 10MHz from Rubbitinn unit -> low pass -> 25MHz xta