mini organ operates on light

[AyaSul]

Hello;

In the attached circuit-the mini organ toy circuit , i want to replace the push buttons with a light sensor , so when the light is blocked by a hand or any thing (this mimic releasing a key **broken link removed**) , and then the light is passed again . So the piano think that the key is pressed ! and the sound is heard
i tried a photo resistor , but it didn't work .

can any body help me with that ?

thank you

 

[andre_luis]

Probably you can do that by replacing each switch for a circuit composed by a comparator and a LDR device:



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[AyaSul]

but the other terminal of the switch is connected to pin2 of the 555 IC , this circuit is connected to ground ?

 

[andre_luis]

At output of that circuit, you can select some options to perform switch function, such as MOSFET, Opto-coupler, etc...


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[AyaSul]

i will try it
another question , how the circuit would be if i use a photo transistor ? and which is more effective ? and can u please tell me a little comparison between both ?

 

[andre_luis]

...another question , how the circuit would be if i use a photo transistor ?

Find attached bellow an illustration about what I´m talking.
It was not simulated, but I presume that under some empirical adjusts on values, trend to work:




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[Audioguru]

The circuit will not play music, it only plays buzzing tones. The buzzing tones are not musically related.

The 555 is not designed to drive a load as low as an 8 ohm speaker when it has a 9V supply so the 555 might be destroyed.

If the project is for a child and they hold the speaker to their ear then they will be deafened.