Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

led flashing circuit

Status
Not open for further replies.

andrew2022

New Member
i need a led circuit with 3 leds and 3 inputs. what i need is when input A goes high, LED A lights and sound a buzzer until a silence button is pressed. when the silence button is presed i need the circuit to switch the buzzer off and make the led flash approx once per second and for the led to continue to flash until the input goes low. i need it to do the same for LED B and C with only 1 silence button and using 1 buzzer. i also need it so if 1 input has been silence and anotha input then goes high, for that input to light up and sound the buzzer wile the otha input stays flashing, then when the silence is pressed for both LED's to flash (or even all 3 to flash)

any1 know how this can be done?
 
You could do this with logic chips. A set-reset flipflop will let you implement the reset button.

All of this might be easier with a microcontroller though - logic design has a steeper learning curve than programming a microcontroller. Nigel Goodwin has a tutorial about how to use the PIC microcontroller. The link to it is in the bottom of all his posts.

Brent
 
id rather not use microcontrollers. if it is not possible to have the leds flash then i can easily go without the flash, altho i still need the buzzer to sound every time an input goes high until the silence button is pressed
 
andrew2022 said:
id rather not use microcontrollers. if it is not possible to have the leds flash then i can easily go without the flash, altho i still need the buzzer to sound every time an input goes high until the silence button is pressed

A micro-controller would make it a simple job, using a single chip, and easily changed if required. Otherwise you're looking at multiple chips.

You don't say what's it's for, but presumably it's for a quiz?, to show which of the players pressed the button?.
 
no. itz for my dads shop. there are 3 tills. the idea is that the contol panel is in the office so when till A presses the on button, LED A onn the control panel lights up and a buzzer sounds. when he presses the silence button the LED is to flash and the buzzer stop. once the person on till A has pressed the off button the LED is to go out. the idea behind the flash is so if till A presses the button and it is silenced then flashing, if till C then presses the button their LED stays lit and the buzzer sounds so he knows till C is the till which has just puched the button. if it is too complicated to have it with the flashing then i could just use the buzzer with the silence and have nothing flash
 
It isn't the flashing thats hard its all the different situations the circuit has to respond to.

You could do most of this with Set-Reset(SR) flopflops. If you used two SR flopflops for each person, A,B,C(6 total). The simple schematic I've attached should do most of what you want.

You will just need to buy a octal SR flipflop IC an Octal AND gate for the LED enables. And a quad OR gate (you can make a three input or gate from three 2 input OR gates). Then all you need is a 555 timer to make a square wave for your LED flashing and some buzzer circuitry.

Hope this helps
Brent
 

Attachments

  • schm1user.jpg
    schm1user.jpg
    22.4 KB · Views: 422
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top