•  
  •  

DayLight Alarm

The circuit presented here wakes you up with a loud alarm at the break of the daylight. Once again the 555 timer is used here. It is working as an astable multivibrator at a frequency of about 1kHz.
The circuit’s operation can be explained as follows:

When no light falls on the LDR, the transistor is pulled high by the variable resistor. Hence the transistor is OFF and the reset pin of the 555 is pulled low. Due the this the 555 is reset.
When light falls on the LDR, its resistance decreases and pulls the base of the transistor low hence turning it ON. This pulls the reset pin 4 of the 555 high and hence enables the 555 oscillator and a sound is produced by the speaker.

The variable 100K resistor has to be adjusted to set the light intensity that triggers the alarm.

If there are any problems please contact webmaster@electronic-circuits-diagrams.com

Please share & like

Processor Tray LGA2011 Socket for Intel Xeon E5 E5 V2 E7 V2 & i7 CPU - 4 fits 40
$23.99 Processor Tray LGA2011 Socket for Intel Xeon E5 E5 V2 E7 V2 & i7 CPU - 4 fits 40 picture
Intel Xeon SL6VP 3066DP/512/533​/1.525V CPU Processor Socket 604
$10.89  Intel Xeon SL6VP 3066DP/512/533​/1.525V CPU Processor Socket 604  picture
Trenton single board computer 2 x Xeon quad 2.53 24gb JXT6966 PEX10 sbc
$199.99 Trenton single board computer 2 x Xeon quad 2.53 24gb JXT6966 PEX10 sbc picture
GEORGE W GALES DCR-5MX XEON MERCURY POWER SUPPLY
$99.99 GEORGE W GALES DCR-5MX XEON MERCURY POWER SUPPLY picture
Trenton 92-006313-XXX Dual Xeon CPU 3.6 GHz SBC Single Board Computer W/4GB RAM
$49.99 Trenton 92-006313-XXX Dual Xeon CPU 3.6 GHz SBC Single Board Computer W/4GB  RAM picture