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This device is a simple timer, allowing to keep on the headlights of your vehicle for about 1min. and 30sec., e.g. when accessing some dark place, without the necessity of coming back to switch-off the lights. Pushing on P1 allows C1 charging to full 12V battery supply. Therefore Q1 is driven hard-on, driving in turn Q2 and its Relay load. The headlights are thus activated by means of the Relay contact wired in parallel to the vehicle's headlights switch. RL1 remains activated until C1 is almost fully discharged, i.e.... [read more]

Almost all 24V power systems in trucks, 4WDs, RVs, boats, etc, employ two series-connected 12V lead-acid batteries. The charging system can only maintain the sum of the individual battery voltages. If one battery is failing, this circuit will light a LED. Hence impending battery problems can be forecast. The circuit works by detecting a voltage difference between the two series connected 12V batteries. Idle current is low enough to allow the unit to be permanently left across the batteries.... [read more]

This Keypad is suitable for the Modular Burglar Alarm. However, it has other applications. Entering the First Four Digits of your chosen Five-Digit code - will energize the relay. Entering the Full Five-Digit code - will de-energize it.... [read more]

The IR detector (IC3) controls an LM 7555 CMOS timer (IC2) which operates in mono stable mode. When the beam is broken, IC2 is triggered and its pin 3 output goes high for about half a second. This extinguishes LED1 and turns on transistor Q1 to drive a 5V low-power relay.... [read more]

The particular circuit combines enough operations, as: [ 1 ] Smooth departure of benefit of AC line of network, with delay 1sec, to the transformers of power supply of amplifier, via the RL1 and the resistance Rx. (see block diagram). [ 2 ] Delay of connection of expenses of final amplifiers, in headphone, in order that noises emanating from the charge - uncharged of capacitors of power supply, they do not pass in them. Simultaneously becomes control of exit of amplifiers for existence of continuous voltage [DC]. If all go well it connects, the amplifiers in loudspeaker.... [read more]

Going camping nowadays involves taking lots of electronic equipment whether for day to day running or for fun and entertainment. Most of the time a charged lead acid battery and a power inverter would be used to ensure a smoothly organized holiday where ideally the missus and the children cheerfully use their electric and electronic gear! With rechargeable lead-acid batteries it’s invariably useful - if not essential - to determine whether the power source you’re hauling along on your travels is losing capacity and needs to be topped up. The same circuit would also come in handy when going on a car or motorbike trip as it can check the status of a 12 V (car) or a 6 V (motorcycle) battery.... [read more]