1. TiltedMag

    555 Timer MOSFET issues

    I am trying to use a monostable 555 timer circuit to control a peristaltic pump. But, the timer duration is not consistent. I replaced the fet and motor with LEDs and the timer behaves as expected (on for ~10s with the pot at 1 Mohm). What else do I need to have the timer drive the fet properly...
  2. A

    Timer Circuit

    Hello, I am trying to make a timer circuit that can hold a FET or a relay high for 4 hrs. and low for 4 hrs. 555 timer is the option I have so far and want to make sure that it can stay that long. are there any better options ?
  3. blink13

    (Trying to know how to do it without 555 IC) How do we generate oscillating signals today?

    It might be a bit broad but I'd like it to confine on the astable operation of the 555 timer. That would be, generating a signal with a certain frequency and pulse width. Although we can also output sawtooth/triangle signal by using the capacitor connected to the 555, so there's also that...
  4. P

    Problem with Ramp signal Generator using IC 555

    According to theory the time period for ramp signal generated using the following circuit should be: \[ \frac{2}{3} \frac{V_{CC}.C_{1}.R_{1}.(R_{1}+R_{2})}{V_{CC}.R_{2}-V_{BE}.(R_{1}+R_{2})} \] Now... putting the value of Vcc, R1, R2, VBE, RE... the time period comes out to be around 0.9ms. But...
  5. E

    Triple-555 timer circuit not working in Proteus

    I am new to 555 Timers and Proteus and I need help to fix a circuit I have built. The intended function of the circuit is as follows. The logic is controlled by an external circuit but it is represented by switches within this circuit to purely test the 555 Timer functionality. The switches...
  6. gamecoder.nz

    1-2MHz square wave generator

    Hi everyone, I am building a breadboard computer and I want a relatively high frequency clock, no more than 2MHz. I have a LMC555, which has a max of 3MHz, and put it into an a-stable configuration with two 27ohm resistors and a 0.01uF capacitor. But I put an LED on the output and it doesn't...
  7. M

    555 timer frequency

    I have a steeper motor that needs a slower step-pulse to get it moving then a faster pulse to increase speed. It needs to start at 1.25hz then increase to 10 hz in a short amount of time. The 555 circuit will be powered on with a trigger limit switch. Then unenergized once the stepper motor...
  8. D

    Using a 555 timer as a timed switch for a USB device?

    Without getting too into the weeds of my project; what I am attempting to do is to control the plugging in and removing of a basic USB device. To accomplish this, I have cut open the USB cable of my USB device and have cut the 5V line. I plan to connect the two sides of the 5V line to two...
  9. D

    Circuit to alert to loitering vehicles by detecting engine idling for more than 2 minutes

    Hi Guys, I'm new here, so apologize if this has already been covered. I would like to know when a vehicle that stops at the stop sign in front of my house just hangs out there for an extended period of time. I'm imagining a circuit with a ceramic mic, audio level detector that triggers a WiFi...
  10. Doktor Jones

    P-channel mosfet and 555 for power-on delay?

    It's been forever and a day since I've been here, but I'm dipping my toes back into electronics design Anyways, I have a "dumb" device that's connected to a hat on my Raspberry Pi 4. Unfortunately, due to some signaling issues with the dumb device, if it's on when the Pi powers on, the Pi gets...
  11. Insignificantinvisiblespo

    555 circuit skin effect?

    Hello. Im new here. I was thinking about making a 555 timer circuit, but im pretty inexperienced and dont know if using a 555 circuit as a switch will cause skin effect. When i think of skin effect i think of a regular household sinewave but i cant imagine what kind of wave would come out of the...
  12. D

    Simple Timer Circuit - Will this circuit work?

    Hi Guys, So I've been trying to wire up a simple timer circuit on a breadboard. I'm a complete novice so I'm just following youtube Tutorials. I found this one video which shows how to do it but It's a little over simplified so I had to fill in a lot of the gaps which may be a source of...
  13. A

    Anyway to auto reset auto off switch using NE555 IC

    I have a need to turn off a load after set duration like 3min(have used different value of Capacitor and resistor) I am using a NE555 IC and going ahead with designing as shown below, my application in breadboard is working but I'll to press switch each time the off timer is needed to activated...
  14. khuranarahul

    Modify Duty cycle by 20 to 50 times

    Hello I have a pulse wave coming from the photo diode, with T(ON) = 50-60us, and total time period is approx 20ms. Since this is too short a period (T1) to be detectable I want to increase it to 5ms, keeping the total time period same, that means I want to multiply the duty cycle by 20 to 30...
  15. J

    Optimizing a circuit

    Hi, Just finished doing my first proper schematic(*) and I'm worried that it's a bloated over engineered lump of components. What I'm trying to do is having 3 LEDs, powered by 2-3 AA batteries fade in and out. I've added a 4th LED which will be on when all 3 are off, I realize that could be...
  16. M

    Amplitude modulation with MCU and NE 555

    Hi, I want to build an IR transmitter (~ 38kHz). My plan is to use a NE555 timer to generate the carrier wave (A-stable Operation), modulate it with a micro controller, and transmit modulated signal via IR LED. My question: Can I connect the micro controller output pin directly to the CONT...
  17. Mariachi


    Hi! Can you help me please? I don't understand why the circuit doesn't work, but it works when the output of timer 555 is also connected to the oscilloscope, although it's the same thing.
  18. S

    Turn 6V motor on/off via 555 timer astable circuit and 5V relay

    I have been working on a circuit to turn a motor on for several seconds, and then off for a longer period, using a 555 astable circuit. The on time needs to be around 5-10 seconds, and the off time needs to be about a minute. To get around the 50% duty cycle issue and allow for a longer off...
  19. Mariachi

    PWM using 555

    I want to make a pwm generator with variable frequency. I notice that the capacitor is charged through R1, but the discharge? I don't know with what formula the duty cycle can be calculated in this case. Thanks!
  20. hopalele74

    Is this a good way to dim a 5-inch LCD for my Raspberry Pi?

    Hi. I'm trying to make a DPI display to work with my Raspberry Pi. First, I searched around and found out that the 555 timer IC is a good way to control the brightness of the display. And since the background LEDs needs around 23V to function, I've included a step up converter. It's for a LCD...