Hello, i posted a thread on how to generate a sawtooth signal with a width of 2.5ms and duty cycle of 0.00049%. thanks to crutschow he build for me a circuit that does it. what i want to do is to add a function to the output that will reverse this exact signal.
i hope i was clear enough, thanks!

 

i want to do is to add a function to the output that will reverse this exact signal.

So you want a triangle with a fast rise and a linear fall?
That could be a little more complex to do.

 

Quick charge a capacitor then discharge it through a constant current source

 

Just reverse the leads.

 

Just reverse the leads.

What leads?

 

I was gona say turn it upside down.......but I didn't.

 

Hi, thanks for the comments. what i meant is in picture number (1). but if someone can show me how to design a diffrent circuit that out put like in the second picture its great too! only a signle reverse pulse with no period. Thanks for your help!

 

How linear do you want the signal to go to zero?
if not important use a P mosfet in series with a 10Ohm resistor to charge capacitor with resistor parallel.

Or if you want it linear use a PIC and count dwn in a resistor network with a small capacitor. Buffer the lot with a opamp.

Picbuster

 

What leads?

I just meant to reverse the polarity of the leads of the oscilloscope that you’re looking at the waveform with.

I’m only half joking. Without knowing what the goal is, maybe that would be good enough.

 

How linear do you want the signal to go to zero?
if not important use a P mosfet in series with a 10Ohm resistor to charge capacitor with resistor parallel.

Or if you want it linear use a PIC and count dwn in a resistor network with a small capacitor. Buffer the lot with a opamp.

Picbuster

thanks for the comment. I tried to use the P mosfet but im still not sure how to do this, can you be more specific on how to? Thanks!

 

thanks for the comment. I tried to use the P mosfet but im still not sure how to do this, can you be more specific on how to? Thanks!

the values from resistors and cap's are frequency depended.
but I am sure that you are able to calculate the values wanted.

Picbuster

 

the values from resistors and cap's are frequency depended.
but I am sure that you are able to calculate the values wanted.

Picbuster

Thank you for your time,I appreciate that! if i understand correct i need to control the input voltage for the reverse pulse, and i need it to be independent.

So you want a triangle with a fast rise and a linear fall?
That could be a little more complex to do.

yes.
It is ok to ask if you can design me a new circuit that will generate reverse sawtooth with 2.5ms width and 0.00049% duty cycle like before? agian, thank you.

 

if you can design me a new circuit that will generate reverse sawtooth with 2.5ms width and 0.00049% duty cycle like before?

How many power supply voltages do you have?

 

How many power supply voltages do you have?

you mean how many transformers?

 

you mean how many transformers?

No.
How many different supply voltages, for example 12V, -12V, etc.

 

No.
How many different supply voltages, for example 12V, -12V, etc.

i have a source for x volts to supply

 

i have a source for x volts to supply

So you have a single source that you can adjust?

 

So you have a single source that you can adjust?

yes.

 

Does the triangle wave need to go to 0V?
It's difficult to get a current source to pull down to 0V with a single supply.

 

Does the triangle wave need to go to 0V?
It's difficult to get a current source to pull down to 0V.

its need to go to 0, but even little above like 100mv+- i guess its ok. thank you.