I'm trying to simulate a low frequency Colpitts oscillator in LTSpice using an NPN darlington and a crystal, and I'm having a lot of trouble...

I'm trying to simulate a low frequency Colpitts oscillator in LTSpice using an NPN darlington and a crystal, and I'm having a lot of trouble getting it to start up. Does anyone have a working one of these? I'm just using a capacitor to simulate the crystal, the parameters I am working with are something like: motional capacitance: 5.3ff ESR = 11k ESI ~ 4500 henries EPR = 100 meg E...

Hello, I made a Bandaxall Class D Oscillator with a 11mm x 7mm pot core transformer and it works quite well. The input is 8VDC and...

Hello, I made a Bandaxall Class D Oscillator with a 11mm x 7mm pot core transformer and it works quite well. The input is 8VDC and the secondary output is 800V peak to peak. The transformer is very difficult (for me) to wind because the secondary uses #46 awg wire and it breaks easily. Also, I would like to use a shorter transformer, around 5mm tall. There are smaller pot cores but ther...

Next: The tunnel diode oscillator. Given an LC wit some Q (read damping), if we can neutralize that R, would it start swinging all by...

Next: The tunnel diode oscillator. Given an LC wit some Q (read damping), if we can neutralize that R, would it start swinging all by itself? Well how do you neutralize a resistor? Simple: put a negative resistor in series or parallel with it. Mr Esaki invented the tunnel diode many years ago, it has, at some point, a negative slope in its I versus U curve. So use a properly biased...

The Baxandall parallel class-D oscillator "squegs" in real life if you build it with a high value inductance in the current feed and...

The Baxandall parallel class-D oscillator "squegs" in real life if you build it with a high value inductance in the current feed and bipolar switches. An LTSpice circuit using the Gummel-Poon model for the bipolar transistors doesn't show this - it settles down to a stable sinusoidal oscillation within less than a hundred cycles. The obvious effect of using a high value inductor is that the...

Could some electronics guru here please clarify this a bit ? I am experimenting with SPICE transient analysis of oscillator, and I am unsure as...

Could some electronics guru here please clarify this a bit ? I am experimenting with SPICE transient analysis of oscillator, and I am unsure as to what to set as the ideal sampling time, given that most oscillators will generate a fundamental and a few harmonics. For example, suppose that I have a 500 MHz differential oscillator, and I set the sampling time as 1/(15.0*time period of fund...

ftp://jjlarkin.lmi.net/Efratom.pdf

ftp://jjlarkin.lmi.net/Efratom.pdf

I'm trying to remember the name of a certain IC. I believe it was a PLL-type frequency synthesizer IC for AM/FM radios, to be used with an...

I'm trying to remember the name of a certain IC. I believe it was a PLL-type frequency synthesizer IC for AM/FM radios, to be used with an external local oscillator. I'm fairly certain it had the prefix SA-something, so it was a former Signetics chip. I don't think it's still in production by NXP, though. Any ideas?

https://www.dropbox.com/s/627ifxuw3rsexj2/EP11_Oscillator.jpg?raw=1 Wonder how that will work. I'll have one of my people try it. It would...

https://www.dropbox.com/s/627ifxuw3rsexj2/EP11_Oscillator.jpg?raw=1 Wonder how that will work. I'll have one of my people try it. It would certainly work with a fast comparator with hysteresis. -- I yam what I yam - Popeye

https://en.wikipedia.org/wiki/File:Royer_oscillator.gif I think the transformer phasing dots are wrong. Or, am I wrong?

https://en.wikipedia.org/wiki/File:Royer_oscillator.gif I think the transformer phasing dots are wrong. Or, am I wrong?

I'm being asked to make some replacement FSK modems for a system I designed about 30 years ago... not much money to be made, really just a...

I'm being asked to make some replacement FSK modems for a system I designed about 30 years ago... not much money to be made, really just a charity job. I originally used the XR2206 as the transmit oscillator, and they are gone. Well, Mouser has one piece for $83. MAX038 is gone, too. Jameco has some 2206 DIPs, which I could scoop up, I guess. Anybody know of a classic analog sinewave gen...

Terahertz radiation source: Compact and simple: https://www.sciencedaily.com/releases/2022/01/220111112018.htm paper: ...

Terahertz radiation source: Compact and simple: https://www.sciencedaily.com/releases/2022/01/220111112018.htm paper: https://aip.scitation.org/doi/10.1063/5.0068114 Interesting on chip construction

IRL I don't think there's anything this configuration of the 'HC74 could do but oscillate; with an RC network from not-Q to not-CLR and D, CLK,...

IRL I don't think there's anything this configuration of the 'HC74 could do but oscillate; with an RC network from not-Q to not-CLR and D, CLK, and not-PRE grounded. But with these models from the Yahoo LTSpice users group the LTSPice time domain looks like it manages to find some other metastable state and sits there spinning its wheels. Can anyone suggest some ICs that could bust i...

I'm just getting started with LTSpice, and played yesterday with some Colpitts oscillators to my satisfaction. Today I tried a Hartley, and I...

I'm just getting started with LTSpice, and played yesterday with some Colpitts oscillators to my satisfaction. Today I tried a Hartley, and I can't understand some of the behaviour I'm seeing. In the attached circuit, I've added an emitter resister in an attempt to reduce the high collector current. Merely increasing the base resistor didn't help until the oscillator stopped entirely. Act...

Hi guys, The 200 MHz. frequency synthesizer thread got me thinking. I could use a 200MHz VFO (say 150 to 250 MHz or something like that) I...

Hi guys, The 200 MHz. frequency synthesizer thread got me thinking. I could use a 200MHz VFO (say 150 to 250 MHz or something like that) I don't need much stability, a part per thousand for a several minutes would be enough. So what's the simplest way to get there? An LC oscillator (I've got some nice tunable few pF caps) There's also a VCO from Maxim. (max2607) that looks easy. http://...

Speaking of SPICE, here's a nice little circuit: https://www.seventransistorlabs.com/Images/BakerDarlington.png I discovered the oscillator on...

Speaking of SPICE, here's a nice little circuit: https://www.seventransistorlabs.com/Images/BakerDarlington.png I discovered the oscillator on the left, when attempting to build a Darlington transistor pair with a Baker clamp. (In practice, R10 comes from a logic voltage input, and R2 is a load, often inductive. R14 is optional, but exacerbates the oscillation, making it reproducible.)...

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 ...

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...

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...

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...