Larkin's Oscillator Explained
in [Design]
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From: George Herold on 15 Jun 2010 21:24 On Jun 15, 5:32 pm, Phil Hobbs <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > George Herold wrote: > > On Jun 15, 2:54 pm, Phil Hobbs > > <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > >> baron wrote: > >>> George Herold Inscribed thus: > >>>> On Jun 14, 3:29 pm, John Larkin > >>>> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >>>>> On Mon, 14 Jun 2010 12:12:17 -0700 (PDT), George Herold > >>>>> <gher...(a)teachspin.com> wrote: > >>>>>> Could someone tell me what squegging is? A google search gives > >>>>>> hints of something like motor-boating, but different? > >>>>> We're referring to an oscillator that oscillates in bursts, rather > >>>>> than continuously. A resonator connected to a negative resistance > >>>>> doesn't squegg, but on the other hand its amplitude builds to > >>>>> infinite (for certain values of infinite) at a rate determined by Q.. > >>>>> You can think of an LC resonator as having a 1st order response, > >>>>> measuring oscillation envelope versus drive. Oscillators squegg when > >>>>> some amplitude limiting mechanism adds additional time delays or > >>>>> memory, more poles in the control loop, like the capacitor in the > >>>>> base of my circuit. A bigger cap reduces the tendency to squegg. > >>>>> A superregen receiver is a squegging-on-purpose RF oscillator. That's > >>>>> a fascinating circuit. > >>>>> John > >>>> Hmm, OK something like motorboating gone to the extreme.. enough > >>>> amplitude modultaion to shut the oscillator off for some time. (?) > >>>> Does the squegg rate stay constant in a sugerregen receiver? I'm not > >>>> real sure what a superregen reciever is, anything like a marginal > >>>> oscillator? > >>>> George H. > >>> Its a technique by which an amplifier is held on the verge of > >>> oscillation by positive feedback, at which point the gain is very high. > >>> By causing the oscillation to be quenched at the instant it starts is > >>> where the "Super" bit comes from in "Superregenerative". Commonly used > >>> in radio receivers where a single active device is used to both amplify > >>> the incoming RF, demodulate it and amplify the resultant AF, often > >>> driving headphones directly. Often frowned upon because of the > >>> interference that can be caused by radiated RF. > >> I think you're confusing it with a Q-multiplier, which is a > >> marginally-stable positive feedback gizmo used to sharpen up crummy RF > >> tank circuits in HF radios. (They're noisy as can be, but you don't > >> care at HF.) > > >> A superregen is an oscillator that gets quenched (i.e. turned on and > >> off) at some more or less fixed ultrasonic frequency like 50 kHz. > >> Quench can be internal (due to squegging or blocking), or can be applied > >> externally. > > >> Since oscillation has to build up from noise, even a small input signal > >> changes the average output level dramatically. The build-up is > >> exponential, so an input signal e times the thermal noise speeds up the > >> build-up by one whole time constant. > > > Excellent! I was reading a few web things about it and this is the > > critical point that I did not see mentioned. > > > Hmm, seems like you might be able to measure changes in noise with a > > super-regen too. (I'm not sure how you would calibrate it.) > > > George H. > > The rushing sound from the speaker is amplified thermal noise. > > Cheers > > Phil Hobbs > > -- > Dr Philip C D Hobbs > Principal > ElectroOptical Innovations > 55 Orchard Rd > Briarcliff Manor NY 10510 > 845-480-2058 > hobbs at electrooptical dot nethttp://electrooptical.net- Hide quoted text - > > - Show quoted text - I've never heard it... sigh. The noise only 'sets' the size of the first oscillation (or so). Ever 50kHz 'squegg' gets a different seed, when listening to noise. (I'm probabbly using squeeg wrong.) The noise in the noise will go like the squegg freq over the carrier. Seems like I'm going to have to try and build one. My son and I can listen to AM radio.
From: George Herold on 15 Jun 2010 21:25 On Jun 15, 5:32 pm, Phil Hobbs <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > George Herold wrote: > > On Jun 15, 2:54 pm, Phil Hobbs > > <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > >> baron wrote: > >>> George Herold Inscribed thus: > >>>> On Jun 14, 3:29 pm, John Larkin > >>>> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >>>>> On Mon, 14 Jun 2010 12:12:17 -0700 (PDT), George Herold > >>>>> <gher...(a)teachspin.com> wrote: > >>>>>> Could someone tell me what squegging is? A google search gives > >>>>>> hints of something like motor-boating, but different? > >>>>> We're referring to an oscillator that oscillates in bursts, rather > >>>>> than continuously. A resonator connected to a negative resistance > >>>>> doesn't squegg, but on the other hand its amplitude builds to > >>>>> infinite (for certain values of infinite) at a rate determined by Q.. > >>>>> You can think of an LC resonator as having a 1st order response, > >>>>> measuring oscillation envelope versus drive. Oscillators squegg when > >>>>> some amplitude limiting mechanism adds additional time delays or > >>>>> memory, more poles in the control loop, like the capacitor in the > >>>>> base of my circuit. A bigger cap reduces the tendency to squegg. > >>>>> A superregen receiver is a squegging-on-purpose RF oscillator. That's > >>>>> a fascinating circuit. > >>>>> John > >>>> Hmm, OK something like motorboating gone to the extreme.. enough > >>>> amplitude modultaion to shut the oscillator off for some time. (?) > >>>> Does the squegg rate stay constant in a sugerregen receiver? I'm not > >>>> real sure what a superregen reciever is, anything like a marginal > >>>> oscillator? > >>>> George H. > >>> Its a technique by which an amplifier is held on the verge of > >>> oscillation by positive feedback, at which point the gain is very high. > >>> By causing the oscillation to be quenched at the instant it starts is > >>> where the "Super" bit comes from in "Superregenerative". Commonly used > >>> in radio receivers where a single active device is used to both amplify > >>> the incoming RF, demodulate it and amplify the resultant AF, often > >>> driving headphones directly. Often frowned upon because of the > >>> interference that can be caused by radiated RF. > >> I think you're confusing it with a Q-multiplier, which is a > >> marginally-stable positive feedback gizmo used to sharpen up crummy RF > >> tank circuits in HF radios. (They're noisy as can be, but you don't > >> care at HF.) > > >> A superregen is an oscillator that gets quenched (i.e. turned on and > >> off) at some more or less fixed ultrasonic frequency like 50 kHz. > >> Quench can be internal (due to squegging or blocking), or can be applied > >> externally. > > >> Since oscillation has to build up from noise, even a small input signal > >> changes the average output level dramatically. The build-up is > >> exponential, so an input signal e times the thermal noise speeds up the > >> build-up by one whole time constant. > > > Excellent! I was reading a few web things about it and this is the > > critical point that I did not see mentioned. > > > Hmm, seems like you might be able to measure changes in noise with a > > super-regen too. (I'm not sure how you would calibrate it.) > > > George H. > > The rushing sound from the speaker is amplified thermal noise. > > Cheers > > Phil Hobbs > > -- > Dr Philip C D Hobbs > Principal > ElectroOptical Innovations > 55 Orchard Rd > Briarcliff Manor NY 10510 > 845-480-2058 > hobbs at electrooptical dot nethttp://electrooptical.net- Hide quoted text - > > - Show quoted text - I've never heard it... sigh. The noise only 'sets' the size of the first oscillation (or so). Ever 50kHz 'squegg' gets a different seed. (I'm probably using squeeg wrong.) The noise in the noise will go like the squegg freq over the carrier. Seems like I'm going to have to try and build one. My son and I can listen to AM radio. George H.
From: Phil Hobbs on 15 Jun 2010 23:22 George Herold wrote: > On Jun 15, 5:32 pm, Phil Hobbs > <pcdhSpamMeSensel...(a)electrooptical.net> wrote: >> George Herold wrote: >>> On Jun 15, 2:54 pm, Phil Hobbs >>> <pcdhSpamMeSensel...(a)electrooptical.net> wrote: >>>> baron wrote: >>>>> George Herold Inscribed thus: >>>>>> On Jun 14, 3:29 pm, John Larkin >>>>>> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>>> On Mon, 14 Jun 2010 12:12:17 -0700 (PDT), George Herold >>>>>>> <gher...(a)teachspin.com> wrote: >>>>>>>> Could someone tell me what squegging is? A google search gives >>>>>>>> hints of something like motor-boating, but different? >>>>>>> We're referring to an oscillator that oscillates in bursts, rather >>>>>>> than continuously. A resonator connected to a negative resistance >>>>>>> doesn't squegg, but on the other hand its amplitude builds to >>>>>>> infinite (for certain values of infinite) at a rate determined by Q.. >>>>>>> You can think of an LC resonator as having a 1st order response, >>>>>>> measuring oscillation envelope versus drive. Oscillators squegg when >>>>>>> some amplitude limiting mechanism adds additional time delays or >>>>>>> memory, more poles in the control loop, like the capacitor in the >>>>>>> base of my circuit. A bigger cap reduces the tendency to squegg. >>>>>>> A superregen receiver is a squegging-on-purpose RF oscillator. That's >>>>>>> a fascinating circuit. >>>>>>> John >>>>>> Hmm, OK something like motorboating gone to the extreme.. enough >>>>>> amplitude modultaion to shut the oscillator off for some time. (?) >>>>>> Does the squegg rate stay constant in a sugerregen receiver? I'm not >>>>>> real sure what a superregen reciever is, anything like a marginal >>>>>> oscillator? >>>>>> George H. >>>>> Its a technique by which an amplifier is held on the verge of >>>>> oscillation by positive feedback, at which point the gain is very high. >>>>> By causing the oscillation to be quenched at the instant it starts is >>>>> where the "Super" bit comes from in "Superregenerative". Commonly used >>>>> in radio receivers where a single active device is used to both amplify >>>>> the incoming RF, demodulate it and amplify the resultant AF, often >>>>> driving headphones directly. Often frowned upon because of the >>>>> interference that can be caused by radiated RF. >>>> I think you're confusing it with a Q-multiplier, which is a >>>> marginally-stable positive feedback gizmo used to sharpen up crummy RF >>>> tank circuits in HF radios. (They're noisy as can be, but you don't >>>> care at HF.) >>>> A superregen is an oscillator that gets quenched (i.e. turned on and >>>> off) at some more or less fixed ultrasonic frequency like 50 kHz. >>>> Quench can be internal (due to squegging or blocking), or can be applied >>>> externally. >>>> Since oscillation has to build up from noise, even a small input signal >>>> changes the average output level dramatically. The build-up is >>>> exponential, so an input signal e times the thermal noise speeds up the >>>> build-up by one whole time constant. >>> Excellent! I was reading a few web things about it and this is the >>> critical point that I did not see mentioned. >>> Hmm, seems like you might be able to measure changes in noise with a >>> super-regen too. (I'm not sure how you would calibrate it.) >>> George H. >> The rushing sound from the speaker is amplified thermal noise. >> >> Cheers >> >> Phil Hobbs >> >> -- >> Dr Philip C D Hobbs >> Principal >> ElectroOptical Innovations >> 55 Orchard Rd >> Briarcliff Manor NY 10510 >> 845-480-2058 >> hobbs at electrooptical dot nethttp://electrooptical.net- Hide quoted text - >> >> - Show quoted text - > > I've never heard it... sigh. The noise only 'sets' the size of the > first oscillation (or so). Ever 50kHz 'squegg' gets a different > seed. (I'm probably using squeeg wrong.) The noise in the noise will > go like the squegg freq over the carrier. Seems like I'm going to > have to try and build one. My son and I can listen to AM radio. > > George H. Or even FM. Of course due to the logarithmic response the AM is sort of distorted. You can also run a superregen in linear mode, by speeding up the quench so that the oscillation never quite reaches its final amplitude. That's quite a bit tweakier, though. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: George Herold on 16 Jun 2010 11:39 On Jun 15, 11:22 pm, Phil Hobbs <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > George Herold wrote: > > On Jun 15, 5:32 pm, Phil Hobbs > > <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > >> George Herold wrote: > >>> On Jun 15, 2:54 pm, Phil Hobbs > >>> <pcdhSpamMeSensel...(a)electrooptical.net> wrote: > >>>> baron wrote: > >>>>> George Herold Inscribed thus: > >>>>>> On Jun 14, 3:29 pm, John Larkin > >>>>>> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >>>>>>> On Mon, 14 Jun 2010 12:12:17 -0700 (PDT), George Herold > >>>>>>> <gher...(a)teachspin.com> wrote: > >>>>>>>> Could someone tell me what squegging is? A google search gives > >>>>>>>> hints of something like motor-boating, but different? > >>>>>>> We're referring to an oscillator that oscillates in bursts, rather > >>>>>>> than continuously. A resonator connected to a negative resistance > >>>>>>> doesn't squegg, but on the other hand its amplitude builds to > >>>>>>> infinite (for certain values of infinite) at a rate determined by Q.. > >>>>>>> You can think of an LC resonator as having a 1st order response, > >>>>>>> measuring oscillation envelope versus drive. Oscillators squegg when > >>>>>>> some amplitude limiting mechanism adds additional time delays or > >>>>>>> memory, more poles in the control loop, like the capacitor in the > >>>>>>> base of my circuit. A bigger cap reduces the tendency to squegg. > >>>>>>> A superregen receiver is a squegging-on-purpose RF oscillator. That's > >>>>>>> a fascinating circuit. > >>>>>>> John > >>>>>> Hmm, OK something like motorboating gone to the extreme.. enough > >>>>>> amplitude modultaion to shut the oscillator off for some time. (?) > >>>>>> Does the squegg rate stay constant in a sugerregen receiver? I'm not > >>>>>> real sure what a superregen reciever is, anything like a marginal > >>>>>> oscillator? > >>>>>> George H. > >>>>> Its a technique by which an amplifier is held on the verge of > >>>>> oscillation by positive feedback, at which point the gain is very high. > >>>>> By causing the oscillation to be quenched at the instant it starts is > >>>>> where the "Super" bit comes from in "Superregenerative". Commonly used > >>>>> in radio receivers where a single active device is used to both amplify > >>>>> the incoming RF, demodulate it and amplify the resultant AF, often > >>>>> driving headphones directly. Often frowned upon because of the > >>>>> interference that can be caused by radiated RF. > >>>> I think you're confusing it with a Q-multiplier, which is a > >>>> marginally-stable positive feedback gizmo used to sharpen up crummy RF > >>>> tank circuits in HF radios. (They're noisy as can be, but you don't > >>>> care at HF.) > >>>> A superregen is an oscillator that gets quenched (i.e. turned on and > >>>> off) at some more or less fixed ultrasonic frequency like 50 kHz. > >>>> Quench can be internal (due to squegging or blocking), or can be applied > >>>> externally. > >>>> Since oscillation has to build up from noise, even a small input signal > >>>> changes the average output level dramatically. The build-up is > >>>> exponential, so an input signal e times the thermal noise speeds up the > >>>> build-up by one whole time constant. > >>> Excellent! I was reading a few web things about it and this is the > >>> critical point that I did not see mentioned. > >>> Hmm, seems like you might be able to measure changes in noise with a > >>> super-regen too. (I'm not sure how you would calibrate it.) > >>> George H. > >> The rushing sound from the speaker is amplified thermal noise. > > >> Cheers > > >> Phil Hobbs > > >> -- > >> Dr Philip C D Hobbs > >> Principal > >> ElectroOptical Innovations > >> 55 Orchard Rd > >> Briarcliff Manor NY 10510 > >> 845-480-2058 > >> hobbs at electrooptical dot nethttp://electrooptical.net-Hide quoted text - > > >> - Show quoted text - > > > I've never heard it... sigh. The noise only 'sets' the size of the > > first oscillation (or so). Ever 50kHz 'squegg' gets a different > > seed. (I'm probably using squeeg wrong.) The noise in the noise will > > go like the squegg freq over the carrier. Seems like I'm going to > > have to try and build one. My son and I can listen to AM radio. > > > George H. > > Or even FM. Of course due to the logarithmic response the AM is sort of > distorted. You can also run a superregen in linear mode, by speeding up > the quench so that the oscillation never quite reaches its final > amplitude. That's quite a bit tweakier, though. > > Cheers > > Phil Hobbs > > -- > Dr Philip C D Hobbs > Principal > ElectroOptical Innovations > 55 Orchard Rd > Briarcliff Manor NY 10510 > 845-480-2058 > hobbs at electrooptical dot nethttp://electrooptical.net- Hide quoted text - > > - Show quoted text - I don't quite 'see' how it works with FM, but that's OK. I guess AM at 1MHz just sounded easier than FM at 100MHz. Oh I was thinking of a linear mode... tweaky, gives you something to do. It's really pretty neat that with one amp you can from noise levels up to volts. George H.
From: John Larkin on 16 Jun 2010 12:14 On Wed, 16 Jun 2010 08:39:19 -0700 (PDT), George Herold <gherold(a)teachspin.com> wrote: >On Jun 15, 11:22�pm, Phil Hobbs ><pcdhSpamMeSensel...(a)electrooptical.net> wrote: >> George Herold wrote: >> > On Jun 15, 5:32 pm, Phil Hobbs >> > <pcdhSpamMeSensel...(a)electrooptical.net> wrote: >> >> George Herold wrote: >> >>> On Jun 15, 2:54 pm, Phil Hobbs >> >>> <pcdhSpamMeSensel...(a)electrooptical.net> wrote: >> >>>> baron wrote: >> >>>>> George Herold Inscribed thus: >> >>>>>> On Jun 14, 3:29 pm, John Larkin >> >>>>>> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>>>>> On Mon, 14 Jun 2010 12:12:17 -0700 (PDT), George Herold >> >>>>>>> <gher...(a)teachspin.com> wrote: >> >>>>>>>> Could someone tell me what squegging is? �A google search gives >> >>>>>>>> hints of something like motor-boating, but different? >> >>>>>>> We're referring to an oscillator that oscillates in bursts, rather >> >>>>>>> than continuously. A resonator connected to a negative resistance >> >>>>>>> doesn't squegg, but on the other hand its amplitude builds to >> >>>>>>> infinite (for certain values of infinite) at a rate determined by Q.. >> >>>>>>> You can think of an LC resonator as having a 1st order response, >> >>>>>>> measuring oscillation envelope versus drive. Oscillators squegg when >> >>>>>>> some amplitude limiting mechanism adds additional time delays or >> >>>>>>> memory, more poles in the control loop, like the capacitor in the >> >>>>>>> base of my circuit. A bigger cap reduces the tendency to squegg. >> >>>>>>> A superregen receiver is a squegging-on-purpose RF oscillator. That's >> >>>>>>> a fascinating circuit. >> >>>>>>> John >> >>>>>> Hmm, OK something like motorboating gone to the extreme.. enough >> >>>>>> amplitude modultaion to shut the oscillator off for some time. (?) >> >>>>>> Does the squegg rate stay constant in a sugerregen receiver? � I'm not >> >>>>>> real sure what a superregen reciever is, anything like a marginal >> >>>>>> oscillator? >> >>>>>> George H. >> >>>>> Its a technique by which an amplifier is held on the verge of >> >>>>> oscillation by positive feedback, at which point the gain is very high. >> >>>>> By causing the oscillation to be quenched at the instant it starts is >> >>>>> where the "Super" bit comes from in "Superregenerative". �Commonly used >> >>>>> in radio receivers where a single active device is used to both amplify >> >>>>> the incoming RF, demodulate it and amplify the resultant AF, often >> >>>>> driving headphones directly. �Often frowned upon because of the >> >>>>> interference that can be caused by radiated RF. >> >>>> I think you're confusing it with a Q-multiplier, which is a >> >>>> marginally-stable positive feedback gizmo used to sharpen up crummy RF >> >>>> tank circuits in HF radios. �(They're noisy as can be, but you don't >> >>>> care at HF.) >> >>>> A superregen is an oscillator that gets quenched (i.e. turned on and >> >>>> off) at some more or less fixed ultrasonic frequency like 50 kHz. >> >>>> Quench can be internal (due to squegging or blocking), or can be applied >> >>>> externally. >> >>>> Since oscillation has to build up from noise, even a small input signal >> >>>> changes the average output level dramatically. �The build-up is >> >>>> exponential, so an input signal e times the thermal noise speeds up the >> >>>> build-up by one whole time constant. � >> >>> Excellent! �I was reading a few web things about it and this is the >> >>> critical point that I did not see mentioned. >> >>> Hmm, seems like you might be able to measure changes in noise with a >> >>> super-regen too. � (I'm not sure how you would calibrate it.) >> >>> George H. >> >> The rushing sound from the speaker is amplified thermal noise. >> >> >> Cheers >> >> >> Phil Hobbs >> >> >> -- >> >> Dr Philip C D Hobbs >> >> Principal >> >> ElectroOptical Innovations >> >> 55 Orchard Rd >> >> Briarcliff Manor NY 10510 >> >> 845-480-2058 >> >> hobbs at electrooptical dot nethttp://electrooptical.net-Hide quoted text - >> >> >> - Show quoted text - >> >> > I've never heard it... sigh. �The noise only 'sets' the size of the >> > first oscillation (or so). �Ever 50kHz 'squegg' gets a different >> > seed. �(I'm probably using squeeg wrong.) �The noise in the noise will >> > go like the squegg freq over the carrier. �Seems like I'm going to >> > have to try and build one. �My son and I can listen to AM radio. >> >> > George H. >> >> Or even FM. �Of course due to the logarithmic response the AM is sort of >> distorted. �You can also run a superregen in linear mode, by speeding up >> the quench so that the oscillation never quite reaches its final >> amplitude. �That's quite a bit tweakier, though. >> >> Cheers >> >> Phil Hobbs >> >> -- >> Dr Philip C D Hobbs >> Principal >> ElectroOptical Innovations >> 55 Orchard Rd >> Briarcliff Manor NY 10510 >> 845-480-2058 >> hobbs at electrooptical dot nethttp://electrooptical.net- Hide quoted text - >> >> - Show quoted text - > >I don't quite 'see' how it works with FM, but that's OK. I guess AM >at 1MHz just sounded easier than FM at 100MHz. Oh I was thinking of a >linear mode... tweaky, gives you something to do. It's really pretty >neat that with one amp you can from noise levels up to volts. > >George H. A superregen makes a decent noise generator. John
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