Ok guys i am a complete newbie when it comes to building circuits and im 100% lost on this so thats why im here. Alright here here is my project. I need to have a 5 second delay on my circuit before turning on and flashing 20 LED lights at the same time and sounding off a buzzer. So here the things i need to happen in 3 different versions of this.


1 555 timer that will wait 5 seconds before flashing 20 LEDs and sounding off a buzzer on a 12v system.

1 555 timer that will wait 5 seconds before turning on 20 LEDs (no flashing) on a 12v system.

1 555 timer that will wait 5 seconds before flashing 20 LEDs (no buzzer) on a 12v system.


I have a little bread board and im not to keen on understanding schems but a breadboard drawing i can better understand.

This is basicly for a simulated flash bangs.

Is any of thise possible with 1 555 timer or does this system require 2 555 timers?

Thanks.

 

you could do it with (1) 555 timer and a microcontroller like an Arduino or BASIC stamp.

it would require several input buttons and user input.

 

you could do it with (1) 555 timer and a microcontroller like an Arduino or BASIC stamp.

it would require several input buttons and user input.

If using a microcontroller, there would not be a need for the 555, the uc can do all the timing...... and it would be a lot easier to implement....


B. Morse

 

if the micro had PWM output yes.

if not, youd need a 555 or other similar, correct?

 

if the micro had PWM output yes.

No, it does not NEED a PWM output: the micro could just turn on an output, wait a while, turn off the output, wait a while, etc. During the wait time, it could be monitoring the inputs to see if they changed. In this simple case PWM would be overkill.

--Rich

 

I think that using a microprocessor is over-kill, but I just don't like microprocessors. I think (2) 555 chips will do the job. One for "wait 5 seconds" and one for "flashing". The other decisions could be done with SPST switches.

There was no request for ending the process, so I can't say how that would be done. Probably just turn off the power.

 

I think that using a microprocessor is over-kill, but I just don't like microprocessors. I think (2) 555 chips will do the job. One for "wait 5 seconds" and one for "flashing". The other decisions could be done with SPST switches.

There was no request for ending the process, so I can't say how that would be done. Probably just turn off the power.

I dont mind using 2 555 timers and i can get the system to flash just fine i just cant seem to figure out the circuit to make it delay 5 seconds before turning on.

I do not want the system to turn off till i turn the power off. The button will actually be a slide switch nothing more. Flip the switch on it delays 5 seconds and then activates the flashing LEDs/buzzers and they do NOT stop until the switch is flipped back off again.

I am trying to keep the system as simple as possible at the lowest cost in materials as possible. All this stuff also has to fit into a 4" acrylic ball. The batteries are going to be LR44 1.5v 150mAh x8 to = 12v @ 150mAh. The standard LEDs are 3v @20 mA. I have not selected the buzzers yet but i would like the system to last for 1 hour before the batteries need to be replaced. I have over 500 LR44 batteries to use so the qty of batteries isnt an issue it is a matter of getting enough of them wired in to fit in the ball with all the LEDs and buzzer that will have a 1 hour run time.

 

OK. A 556 chip is just (2) 555 chips in a single package. You need a "one shot" design for the 5 second "wait". I'll go look it up.

 

Notes: It's a Mouser 511-TS556CN
It's a CMOS 556
The pin numbers can be found in the datasheet.
I hope it works.

 

DX3 thanks so much for the help. I am using actual 555 timers as i have about 100 of them laying around. Rather than buying 556 CMOS chips can i just use two separate 555 timers?

 

Yeahbut...
The 555's won't like the 10 meg resistor unless they are the CMOS version.
You might have to use a 1 meg and a 4.7 uf cap.

 

A passing thought...if you are going to turn these off, and back on, you should put an intentional leak on the first time constant. Maybe 1 meg to charge the first 5 seconds, and 10 megs to ground so they will be reset in about 50 seconds after you turn them off...or you could use a DPDT for the power switch to ground the first capacitor when you turn them off. That will reset the 5 second timer.

 

A passing thought...if you are going to turn these off, and back on, you should put an intentional leak on the first time constant. Maybe 1 meg to charge the first 5 seconds, and 10 megs to ground so they will be reset in about 50 seconds after you turn them off...or you could use a DPDT for the power switch to ground the first capacitor when you turn them off. That will reset the 5 second timer.

That means about about someone speaking in Russian HAHA. I am a complete electronics noob sorry.

I have been looking over your schematic and it is such a small picture and I am not versed with the symbols your using. Is there anyway you could make one using the 555 timer x2 in something i could better understand?

Also yes i will be turning the devices on and off throughout the event and would need them to reset as quick as possible. A 5 second reset once powered off sounds like the option id like to go for.

Thanks again.

 

Here is a simple circuit using two 555's. It flashes at 52 Hz and delays about 5.2 seconds. All timings are ±20% tolerance. CMOS timers (TLC555) should work for low power, but any 555 can be used.

I actually would recommend you just run this from 4x1.5V cells or 6 volts. It'll be more efficient and smaller. You could even, if you want to run it from 6 volts, fit in two CR2032 lithium batteries (3V each), for extended life.

 

Here is a simple circuit using two 555's. It flashes at 52 Hz and delays about 5.2 seconds. All timings are ±20% tolerance. CMOS timers (TLC555) should work for low power, but any 555 can be used.

I actually would recommend you just run this from 4x1.5V cells or 6 volts. It'll be more efficient and smaller. You could even, if you want to run it from 6 volts, fit in two CR2032 lithium batteries (3V each), for extended life.

Tom66. I will try this out see if i can get your schematic to work for me. Wish me luck HAHA. Does this method include what Dex was saying on a reset for when the system is powered down to allow it when turned back on to again function the way of its intent?

 

The drawing I did is directly convertable to 555 chips by changing the pin labels. It was difficult to get it scanned the right size (which I did badly at). I will now try to convert the labels by looking at the attached datasheet.

Pin 1 is discharge
pin 2 is threshold
pin 3 is control voltage
pin4 is reset
pin 5 is output
Pin 6 is trigger
Pin 7 is ground
pin 8 is trigger 2
Pin 9 is output 2
pin 10 is reset 2
pin 11 is control voltage 2
pin 12 is threshold 2
pin 13 is discharge 2
pin 14 is positive power supply

All of these pins canbe found on a datasheet for a "normal" 555 chip (datasheet attached).

I think the way to reset the timers would be to use a power switch that shorts the first capacitor to ground when you turn the device off. That would reset it in a few milliseconds.

 

Tom66. I will try this out see if i can get your schematic to work for me. Wish me luck HAHA. Does this method include what Dex was saying on a reset for when the system is powered down to allow it when turned back on to again function the way of its intent?

The circuit includes the discharge resistor yes. However I don't think it's necessary as the 555 discharges the capacitor when the output goes off. I included just in case (and to show you what it would look like), you should be able to omit it no problems.

Build it in stages. Get the monostable (first half) working before the oscillator (second half).

 

One of the best things about .PNG files is that you can open them in a viewer and zoom in...make them larger so you can see what's going on.

This drawing has the pin numbers for 555 chips.

 

The circuit includes the discharge resistor yes. However I don't think it's necessary as the 555 discharges the capacitor when the output goes off. I included just in case (and to show you what it would look like), you should be able to omit it no problems.

Build it in stages. Get the monostable (first half) working before the oscillator (second half).

I already have the osculating system done without the NPN transistor in place although my bread board can handle two separate circuits at the same time so i ca at least leave my work untouched to build the second system before linking them together.

I will use both schematics the one from you and DX to see which one works the best for me and post the results for you guys. Thanks for all the help if i get stuck ill be back HAHA.

 

Ok guys i tried both circuits but they did not work for me. I was able to find a schematic that did work for me well but now i am going to complicate the circuit even more. I have attached a schematic of what i am trying to accomplish and the basic circuit that is NOT working for me. I am trying to now place a Delay Off circuit in place with a 15 second on time before shutting the entire system down. Here is the logic i am thinking of how i want it to work.

Power is turned on to the flash bang, you make a selection with the selector switch to bypass the 15 second delay off circuit or use it. If using the delay off it, you press the button to trigger the system it turns on and beings counting down 15 seconds before shutting down, at the same time the delay on circuit is counting down 5 seconds to turn the LEDs/Buzzer on. At the end of 5 seconds the LEDs/Buzzers are going off and 10 seconds later the entire flash bag shuts down. If using the bypass circuit you press the same trigger button and the delay on starts the countdown on the 5 seconds before turning on the buzzer/LEDs which will stay on until the power rocker switch is manually turned off.

The image below is the simple circuit i am trying to get to work but it is not working for me.

The image below is the full circuit i am trying to make. It seems as though on this system if power reaches pin 3 of any of the 555 chips, that circuit will activate and keep the system from shutting off or doing what it is intended to do. Also should i use any NPN transistors for any of these systems to amplify the power on any pin 3s? Likely should i use a diode to stop power from passing into Pin 3 when attempting to bypass the delay off circuit or like wise to keep the bypass circuit from getting power through pin 3? I assume i need a diode for this.

So far the only system i have working correctly is the 5 second on delay and the flashing lights. Any revisions to the final circuit would be of great help to me. Thanks guys.