•  
  •  

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

RADIO FREQUENCY SYSTEMS AISG System Cable CA005-7 NSFP CA0057 FREE FAST SHIPPING
$19.99 RADIO FREQUENCY SYSTEMS AISG System Cable CA005-7 NSFP CA0057 FREE FAST SHIPPING picture
Struthers Electronics Watts Test Set Radio Frequency AN/USM-298 Parts
$19.99 Struthers Electronics Watts Test Set Radio Frequency AN/USM-298 Parts picture
Vintage Sensitive Research SRI SS S5 0-.1V Radio Frequency Voltmeter Volt Meter
$39.95 Vintage Sensitive Research SRI SS S5 0-.1V Radio Frequency Voltmeter Volt Meter picture
Adiana Radio Frequency Generator FA00701 Powers On Good Condition
$24.99 Adiana Radio Frequency Generator FA00701 Powers On Good Condition picture
Coolskinproducts skin tightening Cavitation RF Tri polar Radio Frequency
$1200.0  Coolskinproducts skin tightening  Cavitation RF Tri polar Radio Frequency  picture

Warning: Unknown: write failed: Disk quota exceeded (122) in Unknown on line 0

Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0