How can I make this circuit smaller

[jasonpm]

Hello Everyone,

I would like some opinions on how i can make this circuit smaller ...

Any help would be appreciated ... I want it down to a very small size around 3cmx3xm , less if possible , also i am not really good at electronics so there might be a obvious solution, also the led has a delay of around 3seconds as that is what i want.

Thanks

 

[kubeek]

Could you draw a schematic off the whole thing? I somehow don´t see how you get that 3sec delay from it. Also, what kind of pressure switch is that and what transistor do you use?

 

[alec_t]

If you want to go really small use Surface Mount parts plus a 3V coin cell as the power source. When you say the LED has a 3 sec delay do you mean it self-oscillates with a 3 sec period? There are no obvious 'delay' components in the pic.

 

[class]

draw it,to get help

 

[jasonpm]

I have just made this , the only thing is i dont have the model of the capacitor and resistor ( I am not sure how much it will matter but i will get these posted here later in the day!

Thank for all your help guys!

 

[kubeek]

You sure that this picture is correct? Because I don´t even know where to start..Two most important things, depending on the switch being on or off, the thing consumes either 90mA or 230mA so it never actually turns off. untill you disconnect the battery. Second thing is that it runs roughly 150mA through the LED which is probably rated for mere 20mA. Hopefully someone will come with a better idea how to achieve what you want.
Was that turn the switch on - the LED ligths up after about three seconds, right?

 

[dougy83]

Most likely the transistor is actually a 2N3904 (i.e. NPN) and the resistor is a whole lot bigger than 100 ohms (the cap is likely larger too). The LED will have a bit more current going through it than it should.

 

[jasonpm]

You sure that this picture is correct? Because I don´t even know where to start..Two most important things, depending on the switch being on or off, the thing consumes either 90mA or 230mA so it never actually turns off. untill you disconnect the battery. Second thing is that it runs roughly 150mA through the LED which is probably rated for mere 20mA. Hopefully someone will come with a better idea how to achieve what you want.
Was that turn the switch on - the LED ligths up after about three seconds, right?

Hello, First of all thanks for your help, yes as soon as the presure switch is pressed it lasts for 3 seconds.

Basically all i want is when a pressure sensor is pressed a led comes on eaither flashing or staying on for 3-5seconds

 

[jasonpm]

Also i have a sensor/light combo that i have taken out of a kids shoe that is perfect. But does anyone know how this will operate ?


Basically the led says flashing for about 6 sec, I can only see a board, batterys , led's and swictch

 

[jasonpm]

Hello , These are all the components of the current circuit.

Transistor - **broken link removed**
Capaciator - **broken link removed**
Resistor - **broken link removed**
Switch - **broken link removed**

Thanks

 

[alec_t]

I can only see a board, batterys , led's and swictch

In this day and age I expect there's also a microcontroller tucked away there somewhere.....a blob about the size of an ant, that handles the timing and LED switching. Isn't that combo a ready-made solution?

 

[jasonpm]

In this day and age I expect there's also a microcontroller tucked away there somewhere.....a blob about the size of an ant, that handles the timing and LED switching. Isn't that combo a ready-made solution?

I have taken this out of a kids shoe, if i can re produce this it will be good

 

[kiran2810]

hello,
if you want the smaller circuit shown above you have to use the surface mount components.
once you finalized your circuit you can go to make it smaller.

 

[alec_t]

if i can re produce this it will be good

You would need to be able to program a SMD micro. Do you have the skills/facilities?

 

[jasonpm]

You would need to be able to program a SMD micro. Do you have the skills/facilities?

No i dont, How can i go about this ?

 

[alec_t]

Start by looking for online tutorials about PIC coding/programming. Check the microcontroller forum on this site. Or you might persuade a forum member to program a chip for you (the coding would be trivial for some of the guys here )

 

[kiran2810]

i think that circuit is not having so many operations that it needs a micro controller.

 

[alec_t]

Agreed, the circuit complexity doesn't justify a microcontroller; but it's an option because of the OP's requirement to minimise the circuit size. To get a 3 sec delay (or 3 sec switching period) without a micro would probably require bulkier components in total (including e.g. an electrolytic capacitor plus a CMOS IC).