Help making a timed flash circuit

[chownsy]

Im trying to design a micro circuit for a project im working on.

The way the circuit needs to work is as follows.

you activate a switch (needs to be off when pressed, up when on) and this then sets off either a 5 second or 10 second timer, Simultaniously it also charges a camera flash capacitor. After 5/10 seconds the timer fires the flash along with a buzzer.

After the flash and buzzer have sounded it needs to switch off until you press a reset button.

The flash needs to come from lots of mini LEDs (Dont know ammount yet)

Needs to be powered on a 1.5v AA battery

The dimensions i have are 20mm diameter and 100mm long with a top area of 40mm x 10mm But swtich also needs to fit in this area)


I had been toying with a disposible camera but i cant work out how the timers etc would fit and if i can get a timer that small.

If people could help this would be fantastic.

 

[magnatro]

Google Image Result for https://farm3.static.flickr.com/2327/1828270262_b76c867954.jpg

can be used for led flasher.
a simple timer using an npn transistor will serve as timer, and a miniature piezo buzzer as beeper

 

[chownsy]

Thank you for that.

Could i be cheeky and ask you to draw me the full diagram including switch, npn transistor and buzzer in there.

Also i need I think 50 mini LEDs how would i wire that into that system and would i need capacitors etc.

Im good with soldering and understanding wiring diagrams, but im terrible at drawing them and finding the parts i need with out a wiring diagram to follow.

The buzzers, I would, i think need it to be very loud (needs to be able to be heard 3m away in open ground with other noises going on around it)

 

[magnatro]

can design one

 

[chownsy]

In the link you sent me, the LED is permently on, I need it to flash for 1 second and then stay off. Hence thinking along the lines of the camera flash

Also i want to flash 50 LEDs and the buzzer at once, but needs to be delayed from the switch being pressed until the flash. (hence timer)

Here is a quick diagram i drew (wont work i dont think) but its to try and explain how it works.

**broken link removed**

I am willing to pay a little towards someone drawing the diagram and also listing the parts i need as this is something i been struggling with for some time and would like to sort it once and for all.

 

[magnatro]

this might help (i think)

 

[chownsy]

Can you treat me as a complete novice on this and explain that diagram a little more (i can read 90% of it but what is the IC1 and IC2 (HA555N) as google search and searching rs comoponents brings up nothing.

Thank you for all the help your giving me tho

 

[magnatro]

NE 555 (timer)

 

[chownsy]

Thank you for that,

Right im trying to get my head around that circuit diagram.

With my dads help (he is an electrician, but only does machine wiring and not micro electronics) i have kind of got my head around it.

Can you tell me if i am right in this

Activation of the switch (S1) will then activate IC2, this delays the activation of IC1 which then delays the time constant to fire the L1 capacitor linked to the LED's.

While this is happening, IC2 fires SG1 (Buzzer??) before the 2nd timer unit?

Am i right in this so far. If so, can the buzzer and LED's be fired simultaniously and not at different times.

The timers, the time it delays the time by is done by varying the resistors with **broken link removed** this formula?

 

[magnatro]

the ic2 is wired as a multi vibrator
**broken link removed**
the supply for it to work is given by 1st 555
when the output goes high for ic 1, it will trigger both the next ic and the buzzer too.
the inductor acts like a power booster.
the correct expression is given here (for mono stable which provide the delay)
**broken link removed**

 

[chownsy]

That circuit you showed earlier, Did you design that yourself?

Im going to make a list of parts from the RS components website that i use to order my parts from usually, One i have the list, can you check it all to make sure its correct before i purchase anything.

 

[magnatro]

yes it was designed by myself..
ok, i"ll check..

 

[chownsy]

Thank you, If once i have made this prototype and it works, ill send you a £10 or something as a thank you

 

[magnatro]

thanks....!

 

[chownsy]

thanks....!

Thats no problems as i have been tearing my hair out over this for a while.

Im struggling to find all the parts i need, can you take a look on RS Components | Electronic and Electrical Components for me.

I think i worked out these okay

IC1/2 = National Semiconductor | Semiconductors | Clocks and Timing | Timer | Timers/Timing Generators |LMC555CN/NOPB

SG1 = https://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6221427


These are the LED's i think ill be using **broken link removed**

 

[magnatro]

This Will Clear Your Doubts

The monostable multivibrator, shown here will provide the time delay as you press the switch,



the out put wave form will be:

View attachment 5555 test.pdf
//////////////////////////////////////

this is wires to the astable multi-vibrator which drives the LED flash.



the out put wave form will be:

View attachment 55d.pdf
//////////////////////////////////////
the complete circuit will be:


LED used is high bright white LEDS

this is the PCB

View attachment untitled.brd.pdf

pcb top

 

[chownsy]

Man, you are genius

What has taken me weeks of planning you did in 10 minutes.

Could the time delay be varied from 12s to 5s or 7s with the change of a resistor?



What voltage source is needed for the circuit to work, 1.5v or higher (3v lithium cells?)


EDIT: RS components dont seem to have all the parts i need (or there search sucks totally)

Where did oyu get your parts from for this circuit?

 

[magnatro]

yes... it can be changed by adjusting the resistor, or you can use a variable resistor
4.5 volts is recommended, but 3v will do, for more power you can use 4.5 v
the parts are available in you local radio shack or look here Bitsbox - UK Electronic Components Distributor

 

[magnatro]

download and read the attachments. everything is written there..

 

[cowana]

Do bear in mind that this will have the fraction of the power of a regular camera flash.

50 of those white LEDs have a combined input power of about 3.5W (not including resistor losses). A typical camera flash has an input of around 45w per flash. I think you'll find that while quite bright, those LEDs would not light a room to the same degree, or to the same effect (LEDs are much more directional), as a xenon flash.

Also note that magnatro's schematic shows the LEDs wired in series - you would need to wire them in parallel.

Also for the LEDs you have chosen, you will need a 12v supply.

Magnatro, in your schematic of post 6:
- There is no purpose of inductor L1? For a brief pulse of light, the inductor would limit the rise time - surely the flash would be better without it. Adding a capacitor might be a better option if your battery cannot provide a big pulse.
- Pin 3 of the first 555 timer should connect to pin 4 of the other, with 8 on both going to V+. This is the correct way to link two 555s - pin 4 is the reset. Your method is overly complex - also T2 would need to be a PNP transistor for it to work.
- Pin 2 of the first 555 timer needs a pullup (10K should do) to V+.
- The LEDs at the output should be in parallel, and each MUST have a protective resistor. Wired in series, they would not light (especially white LEDs, with a high Vf).

In the schematic in post 16:
- The same issue with the inductor.
- Pin 4 of the second 555 must be high for it to work - the best way to do this is connect it straight to pin 3 of the first, then connect pin 8 of the second to V+. With pin4 floating, the circuit won't work.
- Pin 2 still needs a pullup
- A piezo is the wrong component for SG1 - you need a buzzer (with a driver built in). A piezo would make no sound.
- C7 will stop any DC current getting to the second 555 - it will stop the circuit working.
- Your T2/T3 wiring is wrong (and some NPN/PNP confusion), but they are not needed anyway.
- The same issue with the LEDs and lack of resistors - in your circuit, they would not light up.


Andrew