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 */ ...


44kHz radar time of flight, yes and no

Started by Jan Panteltje in sci.electronics.design9 years ago 6 replies

http://youtu.be/dnrH-7DyGXI This works, increasing the distance between transmitter and receiver increases the delay of the received...

http://youtu.be/dnrH-7DyGXI This works, increasing the distance between transmitter and receiver increases the delay of the received signal. I used a Raspberry Pi to make the on/off pulse, well of course some 555 timers could do it too. A small 2 transistor switch keys the transmitter oscillator driven from a GPIO pin. Youtube resolution is a bit low to see the scope, top trace is tr...


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


Faux MOSFET... Behavioral Modeling

Started by Jim Thompson in sci.electronics.design9 years ago 5 replies

For sometime now I have been trying to build a behavioral model of logic gates that was consistent with real-world behavior when mixed into an...

For sometime now I have been trying to build a behavioral model of logic gates that was consistent with real-world behavior when mixed into an Analog environment. (Existing logic models, such as those in PSpice and LTspice are state machines and do not behave properly when used for Analog applications, such as when you build a crystal oscillator around a 74HCU04.) So I now invite you to ...


RFID tag to erase or zap

Started by blisca in sci.electronics.design6 years ago 3 replies

Good morning, once more i ask for some little help. An item has to be sent to a potential customer,that could became a potential...

Good morning, once more i ask for some little help. An item has to be sent to a potential customer,that could became a potential competitor. Inside a part ,an RFID tag is buried,and i would like that nobody else could read the data in the tag. I tried unsuccessfully to destroy it in 2 ways: 1)An hobbystic Royer oscillator,tuned on the frequency of the tag(125 KHz) 2)An EMP pulse,abou...


massive failure

Started by George Herold in sci.electronics.design10 years ago 5 replies

I made this 'brute force' circuit to try and quench the LED spad. Massive failure. I made an oscillator (again :^) +V bais--1k...

I made this 'brute force' circuit to try and quench the LED spad. Massive failure. I made an oscillator (again :^) +V bais--1k ohm---+-R1-+ | | | \| _ |--R2- ^ to comparator. R | 3 |


PWM controllers... shopping

Started by sea moss in sci.electronics.design2 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.design2 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.design8 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...


Vaccum capacitor failure oddness.

Started by Maynard A. Philbrook Jr. in sci.electronics.design8 years ago 4 replies

While analyzing a problem with a small (150Kwatt oscillator) circuit, we discovered a faulty 200 pf 30VK vacuum cap. This was found via...

While analyzing a problem with a small (150Kwatt oscillator) circuit, we discovered a faulty 200 pf 30VK vacuum cap. This was found via a series of HI-POT testing, starting with the filament transformer (250 amps) which acts as the tube heater and tap for the cathode (-) voltage ( the + is grounded in this circuit) First intentions were to determine if the transformer had a leak...


Radiation RF/Audio

Started by Taylor in sci.electronics.design11 years ago 10 replies

About 60 years ago I had access to a variety of test equipment, including a National receiver capable of receiving signals as low...

About 60 years ago I had access to a variety of test equipment, including a National receiver capable of receiving signals as low as transmitters operating in the audio band. I connected an antenna to the output of an audio oscillator and another on the National HRO?? receiver . To my surprise I had a carrier on the receiver. There was no modulation but if I had modulated the signal w...


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 ...


FPGA temperature measurement

Started by John Larkin in sci.electronics.design9 years ago 15 replies

We're experimenting with heat sinking an Altera Cyclone 3 FPGA. To measure actual die temperature, we built a 19-stage ring...

We're experimenting with heat sinking an Altera Cyclone 3 FPGA. To measure actual die temperature, we built a 19-stage ring oscillator, followed by a divide-by-16 ripple counter, and brought that out. The heat source is the FPGA itself: we just clocked every available flop on the chip at 250 MHz. We stuck a thinfilm thermocouple on the top of the BGA package, and here's what we got: ...


Beyond bizarre mystery HP 204c ailment

Started by don lancaster in sci.electronics.design8 years ago 18 replies

I am in the process of refurbing a HP 204C audio oscillator with its NiCad power supply option. Amazingly, the ancient NiCads seem to...

I am in the process of refurbing a HP 204C audio oscillator with its NiCad power supply option. Amazingly, the ancient NiCads seem to still work. Or at least pretend they do. They DIRECTLY form the +6 -6 supply for the circuit proper. All the power line supposedly does is deliver one of two chosen series current source values to maintain charge. The symptom is this: The output au...


Low voltage negative resistance oscillator design, lessons learned

Started by bitrex in sci.electronics.design3 years ago 121 replies

Don't bother with discretes if you want a negative resistor when you have low psu headroom, all the discrete negative resistance topologies,...

Don't bother with discretes if you want a negative resistor when you have low psu headroom, all the discrete negative resistance topologies, lambda diodes, foldback limiters, etc. are bad at a couple volts and are seriously fussy with respect to how you load them and have lousy tempcos down there. get an AD8515 for 45 cents and save yourself the trouble


Coherence time of MCU class crystal ocsillator?

Started by Vladimir Vassilevsky in sci.electronics.design9 years ago 2 replies

What is the coherence time of a typical MCU class 10 MHz crystal oscillator? I.e. what is the ballpark of time during which the random walk of...

What is the coherence time of a typical MCU class 10 MHz crystal oscillator? I.e. what is the ballpark of time during which the random walk of phase would be 90 degrees rms? Vladimir Vassilevsky DSP and Mixed Signal Designs www.abvolt.com


DIGITALY CONTROLLED RADIO RECEIVER

Started by RealInfo in sci.electronics.design9 years ago 5 replies

Hi all My question is about the structure of a digitally controlled radio like this http://www.hamradio.com/detail.cfm?pid=H0-010818 From...

Hi all My question is about the structure of a digitally controlled radio like this http://www.hamradio.com/detail.cfm?pid=H0-010818 From the point of view of the micro controller that controls it . If I understand well that micro does 3 main things 1> controls the frequency of the PLL that functions as a local oscillator used by the rf mixer 2> sends the relevant data to the


some BFP640 SiGe measurements

Started by John Larkin in sci.electronics.design4 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...


Quartz crystal question

Started by Anonymous in sci.electronics.design7 years ago 15 replies

Could some electronics guru please clarify the following. A quartz crystal, as used in a crustal oscillator, has two characteristic...

Could some electronics guru please clarify the following. A quartz crystal, as used in a crustal oscillator, has two characteristic properties -- series resonance frequency and parallel resonance frequency. How are these two frequencies related to the crystal frequency, i.e., the frequency as advertised for that crystal. Thanks in advance for your help.


Dirt Cheap 2% Full Temperature Accurate Clock Needed

Started by Anonymous in sci.electronics.design5 years ago 49 replies

Hi I need a full temperature range -40 to 105 degrees 2% accurate clock, can be anything from 1MHz to 48MHz I have a micro on the board, but...

Hi I need a full temperature range -40 to 105 degrees 2% accurate clock, can be anything from 1MHz to 48MHz I have a micro on the board, but it has only 5% accuracy clock Looking up resonators they cost about 6 cents in very high volumes I need something at half the price. I have seriously considered doing an ASIC, embedding a good RC oscillator and adding a couple of opamps to the...