Author Topic: Resistive signal to square wave signal  (Read 451 times)

0 Members and 1 Guest are viewing this topic.

Offline Jakkals82Topic starter

  • Newbie
  • Posts: 2
  • Country: za
Resistive signal to square wave signal
« on: October 07, 2026, 12:03:01 pm »
Hi guys

I am trying to build a circuit wth a resistive signal input to create a square wave signal.
I have a 14.2 volt DC input voltage and I THINK I need a 2.3Hz output square wave signal with ~10volts DC.
The resistive signal range is 5.9k Ohm to 0.18k ohm.
The square wave signal needs to increase in frequency as the resistance decreases.
Attached is a circuit diagram that google came up with, as well as a drawing of my interpretaition thereof.
I have build a circuit accordingly, but I am no expert, and yes, it is not working.
Attached is also a component list:
• Voltage Regulator: LM7810 (Outputs a steady 10V from your 14.2V input)
• Timer IC: NE555 (Standard or CMOS version)
• Resistors: One fixed resistor (\(R_{divider}\)) for the sensor, plus R₁ and R₂ for the timer
• Capacitors: One timing capacitor (C₁), plus decoupling capacitors (0.33μ F and 0.1μ F)

I am getting 10 volts after the voltage regulating circuit, but no oscillation.

So maybe my very crude circuit board is a problem, or AI has made a mistake.

Attached is also some pictures of my board.
If anyone can assits I would appreciate it, I am willing to pay for a working solution.
« Last Edit: October 07, 2026, 12:07:18 pm by Jakkals82 »
 

Offline Jakkals82Topic starter

  • Newbie
  • Posts: 2
  • Country: za
Re: Resitive signal to square wave signal
« Reply #1 on: October 07, 2026, 12:06:52 pm »
Two more images:
 

Online themadhippy

  • Super Contributor
  • ***
  • Posts: 4564
  • Country: gb
Re: Resistive signal to square wave signal
« Reply #2 on: October 07, 2026, 01:36:32 pm »
The  third image of the 555 circuit looks a bit odd, 2 pin 8's,the output connected directly to the positive rail,C1 is shorted out, is it si AI?
 

Offline Manul

  • Super Contributor
  • ***
  • Posts: 1407
  • Country: lt
Re: Resistive signal to square wave signal
« Reply #3 on: October 07, 2026, 02:52:04 pm »
Hand drawn schematic looks ok to me, apart from the fact that pin 7 (discharge) seems to be connected to VCC (which is really bad and could damage the IC). And it is draw in a hard to understand layout, the connecting dots also seem missing. So the circuit style needs improvement. And no VCC on pin 7!! The second schematic is some kind AI slop, I'm not going to look at it.
 

Online ledtester

  • Super Contributor
  • ***
  • Posts: 4182
  • Country: us
Re: Resistive signal to square wave signal
« Reply #4 on: October 07, 2026, 03:30:35 pm »
Kill the connection between pin 7 and pin8/10V.

Here is what it appears to be intended:

(Falstad simulation)

The sensor resistance is controlled by the slider on the right. The frequency will change from 1.3 Hz to about 4.4 Hz.

 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf

 

-->