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On off circuit for doll house

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patrickb

New Member
Hi,

Summary:
Can you direct me to a circuit or help me design a circuit that will turn one or more LEDs on.
My goal is to illuminate my daughter's 6 room, 4' high doll house with white LEDs.

Details:
I want to be able to wall mount miniature push-button switchs in each room so that she can push once to turn the room light on and push it again to turn the room's light off.
I also want to have a porch light that works the same way.

I plan to use a 9V DC (350 mA) wall wort to power the house.

The LEDs are rated at 3.0 to 4.2 V. Would I be correct in assuming that each LED would draw ~20mA? I plan to run them at 3.5 V so they're not too bright.
(Here are the LEDs that I'm purchasing: http://sales.goldmine-elec.com/prodinfo.asp?prodid=8100 )

I plan to:
Connect a 275R .25W resistor in series with each LED
Connect all LEDs in parallel to the power source

Thanks in advance for your time and help,


Patrick
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Gene

New Member
Well Pat, sounds like you have it all worked out. You may have a problem finding the resistors you note but you can always go up in value a little. When you buy the transformer, remember that she may turn on all the lights at the same time and select the component with sufficient current to handle the load without over heating. PS. most of these wall devices provide more than 9 volts so don't be surprised if you end up with 10-12 volts and have to re-calculate your resistor values.
 

patrickb

New Member
Thanks for the encouragement Gene,

What can I use to control the lights though? I want to use a single push of a push-button switch to switch a light on, and a single push of the same button to switch it off. I was thinking of using these http://sales.goldmine-elec.com/prodinfo.asp?prodid=8242 relays and these http://sales.goldmine-elec.com/prodinfo.asp?prodid=8324 switches.

My problem is that I can't find a control circuit to close the relays when the button is pushed and then release the relay when the button is pushed again.

Can you advise?

Thanks in advance,


Patrick
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patrickb

New Member
Thank you so much

Sebi,

Thank you so much. I really appreciate your help.

Question: Are the values of the capacitors really 330 nano Farads(nF) or did you mean 330 micro Farads (uF)?

Thanks again,


Patrick
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Sebi

Active Member
the caps as i marked: 330nanofarad. The serialresistor of LEDs depend from supply voltage and LED type. Use a regulated supply for proper work.(the wall adaptor contain only filter cap.)
 

john1

Active Member
Hi Patrick,

I think you can buy little switches,
rather like the top of the old 'press button'
ballpoint pens.

press on, press off.

They can be quite small, and they are very cheap.
Most of them make a nice little 'click'
Using them might be a lot less trouble.

Regards, John :)
 

audioguru

Well-Known Member
Most Helpful Member
Not done yet. :roll:
The CD4069 can't provide enough current to light LEDs very brightly, and the LEDs would load down the outputs so much that the logic won't flip.
Therefore add emitter-followers to the logic outputs to drive the LEDs.

You have enough voltage to wire the LEDs as two in series and reduce the number of current-limiting resistors.

The link to your LEDs didn't work so I assume their "typical" voltage is 3.3V (3.5V is probably their rare max).
 

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eblc1388

Active Member
Although the circuit will work as is, it would be better to replace the values of all the 470K resistors with 4K7, i.e. 4.7K

This helps the circuit to change state faster and performs better at no extra cost.
 

audioguru

Well-Known Member
Most Helpful Member
eblc1388 said:
Although the circuit will work as is, it would be better to replace the values of all the 470K resistors with 4K7, i.e. 4.7K

This helps the circuit to change state faster and performs better at no extra cost.
470k has a response time of about 150ms. 4.7k's time of only 1.5ms would be triggered many times by switch contact bounce. 150k might be a good compromise or use 0.1uF caps with the existing 470k resistors. :lol:
 

eblc1388

Active Member
audioguru said:
470k has a response time of about 150ms. 4.7k's time of only 1.5ms would be triggered many times by switch contact bounce.
The switch contact will bounces but the circuit would not if 4K7 is being use.

Incidentally this is actually the main reason for using a small value resistor in this case.
 

ericgibbs

Well-Known Member
Most Helpful Member
hi Patrick,
These slide switches are really tiny.
Look at this datasheet.

Woops posted to ye olde poste by mistake.!!!
 

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