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Voltage Tester for Model Batteries

Circuit Image : Voltage Tester for Model Batteries Circuit Image

This model battery tester has two functions: it provides a load for the battery, and at the same time it measures the terminal voltage. In addition, both functions can be switched on or off via a model remote-control receiver, to avoid draining the battery when it is not necessary to make a measurement. The load network, which consists of a BC517 Darlington transistor (T2) and load resistor R11 (15 Ω /5 W), is readily evident. When the load is active, the base of T1 lies practically at ground level. Consequently, T1 conducts and allows one of the LEDs to be illuminated.

Circuit Diagram :

Voltage Tester for Model Batteries Circuit Diagram The altogether well known voltmeter circuit, which depends on the LM3914 LED driver, figures out which LED is lit. The estimations of R6 and R7 rely on upon the sort and number of cells in the battery. The goal here is not to quantify the whole voltage range from 0 V, but instead to show the segment of the extent between the completely charged voltage and the completely released voltage. Since a sum of ten LEDs are utilized, the presentation is extremely exact. For a NiCd battery with four cells, the scale keeps running from 4.8 V to 5.5 V when R6 = R7 = 2 kω. The estimation scale for a lithium-particle battery with two cells ranges from 7.2 V to 8.0 V if R6 = 2 kω and R7 = 1 kω.

For remote-control operation, both jumpers ought to be set in the upper position (between pin 1 and the center pin). In this arrangement, either a positive or negative sign edge will begin the estimation process. A positive edge triggers IC1a, whose yield goes High and triggers IC1b. A negative edge has no impact on IC1a, however it triggers IC1b specifically. Regardless, the heap will be enacted for the length of time of the beat from monostable IC1b. Use P12 to set the beat width of IC1a to a sufficient worth, taking care that it is shorter than the beat width of IC1b.

In the event that the voltage analyzer is fitted into a remote-controlled model, you can supplant the jumpers with straightforward wire spans. Then again, on the off chance that you need to utilize it for different purposes, for example, measuring the measure of charge left in a camcorder battery, it is prescribed to unite twofold toss push-catch switches set up of JP1 and JP2. The ordinarily shut contact relates to the upper jumper position,while the regularly open contact compares to the lower position.

Parts :
Resistors:
R1,R2 = 47kΩ
R3 = 100kΩ
R4 = 500kΩ
R5 = 1kΩ
R6,R7 = see text (1% resistors!)
R8 = 1kΩ5
R9 = 1kΩ2
R10 = 330Ω
R11 = 15Ω 5W
R12 = 15kΩ
P1 = 100kΩ preset
Capacitors:
C1 = 10nF
C2 = 100nF
Semiconductors:
D1-D10 = LED, red, high effi-ciency
T1 = BC557
T2 = BC517
IC1 = 74HC123
IC2 = LM3914AN
Miscellaneous:
PC1,PC2,PC3 = solder pin
JP1,JP2 = jumper or pushbutton