Negative pulse generator

[fmnotes]

Hello
knows someone, a circuit for a negative pulse generator?
eg with a 555! ????????
Thank you.

[ANDREAS]

Calculate R1,R2,C1 for duty cycle and out Frequency
You can use power supply <18V. Diodes are not critical
regards

[ANDREAS]

opps sorry for a small false. Remove output elec capacitot 10 uF
Regards

[reza vir]

Hi Andreas
The device can be tested pd & pdk & static & .... ?

[fmnotes]

opps sorry for a small false. Remove output elec capacitot 10 uF
Regards

Thank you my friend Andrea,
I have tried this circuit but I did not found
I have no negative output pulse.
Also I tried to add the little circuit output, and another signal generator but I did and there some negative pulse output.

[ANDREAS]

Remove diode connection ground.
Few years ago, i build it, but i don't remember a small modification. My sense is diode.
I search tomorrow my library, maybe i find it or a better and simple schematic
best regards

[ANDREAS]

Hi Andreas
The device can be tested pd & pdk & static & .... ?

No reza

[reza vir]

Hi dear friend Andreas
This circuit can detect metal ions?
Thanks and regards

[reza vir]

Parts List:

R1 = 100M, 1/2W, 5%
R2 = 10K, 1/4W, 5%
R3 = 5K, potentiometer (see text)
C1 = 470pF, ceramic disc
Led1 = Led, red, 5mm
Q1,Q2 = PN2907 or NTE159M, try others like 2N2907
Q3 = PN2222 or NTE123AP, try others like 2N2222
M1 = 100mA, panel meter

Additional Parts and Materials:

Perfboard, plastic enclosure,
9-volt battery holder and connector,
wire, solder, hardware, etc.

R1 Note:
We couldn't find a 100-mega-ohm resistor.
We used (5) 20-mega-ohm resistors in SERIES to get 100-mega-ohms.

[ANDREAS]

Hi reza
Here is thread "Negative pulse generator" by fmnotes. If you need infos about other circuits-schematic is better open a new thread or go threads from your schematics
About your last schematic , my answer is no!
Best regards

[reza vir]

Thanks Andreas

[fmnotes]

someone else
not aware of any negative pulse circuit?

difficult question