# How can I convert TTL pulse train to current?

#### Ankit Garg

Joined Dec 9, 2016
4
My input is TTL pulse having amplitude +5V, freq from 500KHz to 5Hz and duty cycle 50%.
The output should follow this relationship
I = C * Vc * freq

Where,
Vc= +5V (Pulse Amp)
freq= pulse frequency
C is the capacitor (to be connected in series with the input signal)
The circuit should consists of diodes, capacitors and resistors only..

#### MrChips

Joined Oct 2, 2009
19,728
Is this homework?
So how do you plan on doing this?

#### shteii01

Joined Feb 19, 2010
4,647
I = C * Vc * freq
I take it C and freq are constant. Is that correct?

#### WBahn

Joined Mar 31, 2012
24,966
I take it C and freq are constant. Is that correct?
uh...

My input is TTL pulse having amplitude +5V, freq from 500KHz to 5Hz and duty cycle 50%.
Is this homework?
Sure looks like it.

So how do you plan on doing this?   #### WBahn

Joined Mar 31, 2012
24,966
What is I? The average current? The instantaneous current? The rms current? The current at noon in the River Thames?

Where is this current to be measured?

What attempt(s) have you make so far?

#### Papabravo

Joined Feb 24, 2006
12,684
Think really really hard and propose a possible method. That's what I would do.

#### Ankit Garg

Joined Dec 9, 2016
4
I take it C and freq are constant. Is that correct?
Capacitor value is fixed, input signal frequency is variable (range 5 Hz to 500 KHz)

#### Ankit Garg

Joined Dec 9, 2016
4
What is I? The average current? The instantaneous current? The rms current? The current at noon in the River Thames?

Where is this current to be measured?

What attempt(s) have you make so far?
I is the average current and the circuit shall output current proportional to the input freq.

#### WBahn

Joined Mar 31, 2012
24,966
I is the average current and the circuit shall output current proportional to the input freq.
So is the current supposed to be DC? AC at the same frequency as the input signal?

Where is the current that is being controlled? In the capacitor? In some resistive load?

What attempt(s) have you made so far? Remember, this is YOUR homework problem (and it is pretty obviously a homework problem of some sort). So far we have seen nothing that indicates you are interested in anything more than getting someone else to do your work for you.

#### dannyf

Joined Sep 13, 2015
2,197
The circuit should consists of diodes, capacitors and resistors only..
use a rc network to turn the pulses into charges on the rising and falling edge.

use a diode to gate the charges to either rising or falling edge.

use another diode to direct the charges onto a capacitor.

parallel the capacitor with a large resistor to turn the voltage on the capacitor into a current source.

done.