Circuit-Zone.com - Electronic Projects
Posted on Thursday, October 21, 2010 • Category: Miscellaneous
Not properly closing a refrigerator door will no doubt invite huge electricity bills. This gadget is an alert device that beeps if you leave the refrigerator door open for more than 20 seconds. When the door opens, the lamp illuminates and the IC (a 4060B counter/oscillator) starts counting down. After a preset delay of 20 seconds, the piezoelectric buzzer beeps intermittently for 20 seconds and then stops for the same amount of time. This cycle repeats until the refrigerator door closes.
Posted on Thursday, October 21, 2010 • Category: Motor Controllers
In applications requiring absolute accuracy in the speed control of dc servo motors, thereís no substitute for the traditional tachometer-based feedback loop. But for somewhat less demanding situations, adequate accuracy often can be achieved without the complication and expense of a tach. This can be done by taking advantage of the built-in electromechanical constants of the motor itself.
Posted on Thursday, October 21, 2010 • Category: LED
This is a simple LED torch circuit based on IC MAX660 from MAXIM semiconductors. The MAX 660 is a CMOS type monolithic type voltage converter IC. The IC can easily drive three extra bright white LEDs. The LED's are connected in parallel to the output pin 8 of the IC. The circuit has good battery life. The switch S1 can be a push to ON switch.
Posted on Thursday, October 21, 2010 • Category: Battery Chargers
Here is a lead acid battery charger circuit using IC LM317.The IC here provides the correct charging voltage for the battery. A battery must be charged with 1/10 its Ah value. This charging circuit is designed based on this fact.The charging current for the battery is controlled by Q1,R1,R4 and R5. Potentiometer R5 can be used to set the charging current. As the battery gets charged the the current through R1 increases.
Posted on Thursday, October 21, 2010 • Category: Power Supplies
For circuits using TTL ICs the supply voltage is a great concern and a slight increase in supply from the rated 5V may damage the IC. Using fuses alone does not solve the problem because a fuse may take several milliseconds to blow off and thatís enough time for the IC to get damaged.
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