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Let me see if I understand this correctly:
We start with in1=5V and in2=0 ----->out=5V
The capacitor starts charging from 0 to 5 depending on the CR time constant, so we have a ramp up curve.
After a certain threshold, in2 is supposed to be equal to logic 1 and then the out=0. The capacitor starts to discharge down to the second threshold for the Schmidt Trigger, in2 is supposed to be equal to logic 0 then the output becomes logic one again and this goes on for ever.
If it so I undestand it. Now I have another :
What if the two inputs are short cicuited? Same topology only in1=in2? Then if we start from logic 0 then logic 0 is in the output - no charge of the capacitor.
Suppose now we add a second capacitor and a resistor in series in the output ( see diagram bellow). How does this works? Don't we have a stable logic 0 in the output no matter what? Do I miss something here?
The bjt is used to produce a signal to a transformer. My question is how we end there.
Your two-gate circuit may do something unexpected. U2's output is differentiated by C2 and R2. The resulting signal will try to exceed +5V. U1's input may clamp it or do something else you don't expect. What type of chip is it?
This is the 4093BP using pins 456 and 8910. The npn drives a transformer circuit for 350V dc. This is the circuit producing the input of the tranformer ( I guess). Any ideas?
D.
Your circuit doesnt oscillate
NAnd gates should be also sch. trigger...
U1 inputs tied to 5V over R2 so U1 output will be logic 1 continously and voltage variation at the c2 doesnt effects to U1's inputs..
other hand, diode's which has been tied to transistor is wrong polarity and you should use with a resistor otherwise transistor will be damage.
What kind of circuit looking for? What are you expect from above circuit?
Regards
Added after 9 minutes:
this circuit not suit for H voltage transformer drive..because this is not stable oscillator...you can LM555 osc IC.
Hunter,
I agree with you regarding the oscillation. I run the simulation myself and come up with the same conclusion.
BUT
I have the real thing into my hands and It works!!!
It oscillates with 16.67Hz. This happens in U2 output. U1 output is stable at 5V. Output of the transistor ( 4SD637 is on the real one, but I located only 2SD637) is also oscilating 16.6HZ !!!
I don't know the type of the transformer but it supposed to drive a device that needs 350V DC.
What do you say now?
D.
PS: NAND gates are scmidt trigger gates. I said I use the TC4093BP which is a package of 4 Sch. Trig.
Strange! it can be capture its base signal as noise or somethink like that?
if you select C2 as "microfarad" you can see same oscillation at the U1 as well
but you cant get higher freq. if you sellect lower C value..
BTW 16hz very low for high voltage generator (did i missed Sth)
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