OBJECTIVE
The project under construction here is a DIGITAL STOPWATCH that could count time up to a maximum of 99.9 seconds with a resolution of 0.1sec (or in steps of 0.1 sec) or up to a maximum of 999 seconds with a resolution of 1 second.
This has been possible by having two clock frequency options, a 10Hz clock and a 1Hz clock. This gadget can be used to accurately measure short time intervals. It is portable and operates from four rechargeable Ni-Cd cells.
CIRCUIT DESCRIPTION
IC1 (MM5369) is a popular IC used for generating clock pulses in digital time pieces. lC-1 along with resistors (R1), capacitors (C1) and (C2) and crystal generates a 60 Hz clock signal at its output (Pin-1). This 60Hz clock signal is passed on to the clock input of IC-3 (CD4018B) via an arrangement of read more
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OBJECTIVE
A simple, easy to build portable all electronic resistance meter that can be used to accurately measure resistances up to a maximum of 1MΩ is the project under construction here. The circuit operates from twin 9V batteries. The resistance meter has a linear scale and the zero resistance point appears on the extreme left end of the scale. Another significant feature of this meter is that it can be used to measure resistances without actually taking them out of the circuit.It has six different selectable ranges that permit resistance measurement in decades of (i) 1Ω to 10 Ω (ii) 10 Ω t0 100 Ω (iii) 100 Ω to 1K (iv) 1K to 10K (v) 10K to 100K and (vi) 100K to 1M
CIRCUIT DESCRIPTION
The measurement of resistance in this meter is in terms of voltage developed read more
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OBJECTIVE
Believe it or not, there are numerous occasions when you have switched. on your TV set to watch a specific program of your interest and you found out that there are still a few more minutes to go. The options before you are to either remain glued on to the TV get and wait for your program or switch off the TV set and then switch it on again after sometime. The first option is boring and with the second, you always run the risk of missing a part of the program if you get busy in something else and forget to switch it on in time. Here is a very simple and interesting gadget that could be very easily mounted on your electrical switchboard and which can be used to perform the auto switch on function for your TV set (or fortran matter any other mains operated system) at a time read more
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OBJECTIVE
Here is a simple battery charger circuit, the one that can be used to charge 12 volt batteries of both the usual automobile type as well as the maintenance free sealed lead-acid type. The charger circuit being described here is quite compact can be placed right on the top of the battery required to be charged. In the event of your car battery misbehaving or having become weak, what not require In addition to this gadget. Is only the |230VACmains.230VAC point is quite conveniently available even if you are stuck somewhere on the roadside or – elsewhere far away from a place where you can get your battery charged. This gadget could be one of the most important tools in your tool-kit and you could make use of this gadget to keep your battery healthy. Another significant read more
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