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For an ideal pulse the timeis considered to be zero.
But it depends on the driver capabilities what's the real value.
It is totally independent of frequency, duty cycle and voltage.
For an ideal pulse the timeis considered to be zero.
But it depends on the driver capabilities what's the real value.
It is totally independent of frequency, duty cycle and voltage.
These are just a few, from RC + 3 inverters, single op amp, logic + crystal/logic + RC, two transistor + RC oscillators, the CD4060/HEF4060 + crystal/RC, a VCO IC, ..., ..., and there are plenty more. The "Relaxation Oscillators" pdf has the one using a single op amp and a few discrete components. Not sure why a 555 is not suitable, it's one of the simplest solutions to get a 1kHz, 70% duty cycle and makes it easy to adjust "on" and "off" time.
Attachments
Circuit Techniques for Clock Sources Linear an12fa.pdf
These are just a few, from RC + 3 inverters, single op amp, logic + crystal/logic + RC, two transistor + RC oscillators, the CD4060/HEF4060 + crystal/RC, a VCO IC, ..., ..., and there are plenty more. The "Relaxation Oscillators" pdf has the one using a single op amp and a few discrete components. Not sure why a 555 is not suitable, it's one of the simplest solutions to get a 1kHz, 70% duty cycle and makes it easy to adjust "on" and "off" time.
tnx all . so if i want to design it with 2 tr and resistor and capacitor in base and collector (ASTABLE) i should to first : calculate frequency with ;
so : T1 = ln2 r1c1 = 0.7 ms and T2 = ln2 r2c2 = 0.3 ms (for duty cycle 70%)
I don't think that's so, but I don't know what you mean by "ln2". And the "Relaxation Oscillators" pdf puts f = 1/1.4CR, look at the picture below. You could read pages 5 and 6 if you want to do the BJT version rather than an op amp version as described in the post above yours, there are more pleasant versions of the basic BJT one, such as "Variable Mark to space Ratio."
I don't think that's so, but I don't know what you mean by "ln2". And the "Relaxation Oscillators" pdf puts f = 1/1.4CR, look at the picture below. You could read pages 5 and 6 if you want to do the BJT version rather than an op amp version as described in the post above yours, there are more pleasant versions of the basic BJT one, such as "Variable Mark to space Ratio."
this is correct becuse 1/ln2 = 1.4 and the formule 1/1.4CR in the picture is for duty cycle 50 % with the same R and C in the circuit . ok ?
so i should to writed it T=1.4(C1R2 + C2R3) and by changing c1r2 and c2r3 we can change duty cycle --- F = 216hz >>> T = 4.6ms >>> t1 =3.2 ms >>>t2=1.4 ms >>>> it gives duty cycle 70 %
Not sure, quick calculations for one transistor as "on" and other as "off," assuming you only use 1 output from the oscillator, not both, might be using BJT1 as MARK and BJT2 as SPACE:
9275 isn't a standard value, I'm not up on the standard values for decades of 9, but 21600 is more or less a -1% 22k resistor, typical when you measure batches you buy.
You'd best check the calculations are functionally correct and/or works before using them...
The problem with this kind of thing is that average user like myself purchase capacitors that are usually +-5% to +-20%, and resistors +-1% to +-10%, depending on what you're able/willing to spend, and trimpots are okay but drifty with temp/time/slight vibrations of board for something that needs to be 1kHz. You'd want to measure the passive components to a) separate wheat from chaff, and b) compare calculation to performance.
That depends; if you want accurate frequency and pulse duration (say 1 kHz +/- 1e-3 Hz and pulse width accurate to the third decimal), you have to use digital tools and techniques.
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