Some time's you find some thing good on the internet

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Some time's you find some thing good on the internet

Postby Harry Dalek » Wed Jan 03, 2018 10:59 pm

I came across this which i think is one amazing little circuit i plan on using a little modified on my multi system monitor...
I was shocked at how this simple circuit can duplicate in a way what some high frequency digital circuits and a ADC chips do but pretty much at the same line or frame rate frequencies you want if you replace the opamp oscillator with a sync pulse circuit .
you can see its a great little circuit for a scope tv or crt tv
original and newer videos below and pdf of the circuit

youtu.be/3zZOpDqnj_k

youtu.be/Kqb5zcrgv7s
Attachments
stairstep.pdf
(186.85 KiB) Downloaded 196 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: Some time's you find some thing good on the internet

Postby Steve Anderson » Thu Jan 04, 2018 11:44 am

Yes, quite novel, but be warned, the two oscillators are free-running, they are not locked together. So the number of steps per ramp can vary and drift depending on supply volts, temperature and component tolerances. But if it's what you need then all is OK.

Steve A.
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Re: Some time's you find some thing good on the internet

Postby Harry Dalek » Thu Jan 04, 2018 4:03 pm

Steve Anderson wrote:Yes, quite novel, but be warned, the two oscillators are free-running, they are not locked together. So the number of steps per ramp can vary and drift depending on supply volts, temperature and component tolerances. But if it's what you need then all is OK.

Steve A.



Hi Steve i must admit i was curious what you thought ..
Yes the opamp oscillator is free running i have no interest in this part of the circuit at all only as a demonstration it has a use .
I think the 555 is locked to the free running opamp oscillator via the reset pin 4 but i agree the 555 can be a less than a precise chip needs a regulated supply ...no one here likes oscillators drifting ..... disapproval frown !
I think a sync detection circuit replacing the free running opamp and syncing a oscillator or to a monostable then to the reset of the circuit will be more interesting
Your DAC circuit i am using in the PMT camera works great i am very grateful as i knew nothing of this before you showed me but i did have to replace the clock with a crystal version the 4046 at 3mhz drifted a bit even on a crystal clock it took me a while to adjust components to it to stop any slow drifting .....So both ideas digital and this analog both have their weaknesses and strengths.
Last edited by Harry Dalek on Fri Jan 05, 2018 2:22 pm, edited 1 time in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: Some time's you find some thing good on the internet

Postby Steve Anderson » Fri Jan 05, 2018 11:44 am

Quite right Harry. In my rush yesterday I missed the 555 reset arrangement - so they are locked together. My apologies to the author.

Steve A.
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Re: Some time's you find some thing good on the internet

Postby Harry Dalek » Fri Jan 05, 2018 4:25 pm

Steve Anderson wrote:Quite right Harry. In my rush yesterday I missed the 555 reset arrangement - so they are locked together. My apologies to the author.

Steve A.


No worries Steve ,I put one circuit together over the last 2 days and i have replaced the opamp oscillator with the club IC A and B circuit for the sync testing at 400 hz BTW not using rest of that circuit ..

Testing with Steve's reversing wav grey scale video ....

So pin 7 icB to the base of Q1 this gave with no changes to the stair case circuit results were picture 3 forgive my bad photography adjusting the 555 39k resistor to a lower value its cap from 10nf to 1nf gave many more steps to the ramp and smoothed it out picture 4
Attachments
leddriverckt (1).gif
leddriverckt (1).gif (9.23 KiB) Viewed 2710 times
Screen 00000.jpg
IMG_0649.JPG
IMG_0656.JPG
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4082
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia


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