I have made this circuit http://electroschematics.com/search...ious/alarm/page/2/&ss=&siteurl=/J:/Photodiode Alarm circuit.htm&ref=&ss=&siteurl=/J:/Photodiode Alarm circuit.htm&ref=&ss=
but there is a problem, the alarm still work in two cases because the voltage on pin 4 "rest" even if i don't attach any wire with it is about 0.92 volt (alarm on), so is there a problem in ic 555 or what????

 

Your link DOES NOT WORK.
Please copy and post the schematic HERE to your reply.

The datasheet for the LM555 says, "When the reset function is not in use, it is recommended that it be connected to VCC to avoid any possibility of false triggering."

 

I think this is the circuit the OP is referencing.

 

this is the circuit i think there is a mistake in the connection from T to 4 so i make changes but the problem i talk about is that if i don't attach any wire to 4 the voltage on it is 0.92v so the alarm works this means if i send 0 v to 4 the alarm work too what is the soultion

 

You may try as below:

1. Talking green LED away.
2. Connecting E of T1 to GND.
3. +9V → R4(430Ω) → (+)Green LED 2V/20mA(-) → C of T1
4. R2 changing from 1K to 10K.

* Green LED :
2V/20mA 5mm, using 80% of 20mA is 16mA, R4 = 430Ω
2V/10mA 3mm, using 80% of 10mA is 8mA, R4 = 875Ω,choose 820Ω, about 8.5mA

 

I speak about pin 4 in 555 if i don't attach any wire to it there is a voltage 0.92v on it so is the problem in the ic or what??????

 

The alarm will run with pin 4 disconnected or floating.
Do this:
1. Connect pin 4 to ground, if the alarm still sounds then the IC is not working correctly, replace it.
2. Rewire the circuit as suggested in post #5 This ensures that reset is pulled close to ground, the circuit in post #3 does not do that.

 

I'll try it