TGDA stands for Ting Gadget with Different Applications. It is a multi-purpose ciruit. It can be used for a wide variety of applications varying from domestic to workbench applications. You can use this in a number of ways depending on your innovation, imagination and creativity.
It is basically a resistance-capacitance controlled oscillator to count the pulses for a specific period. If any sensor or transducer such as LDR (Light Dependent Resistor)is connected externally to it, the seven segment display shows the value corresponding to its resistance. Normally open or closed (i.e. contact or break) type transducer can also be used with this gadget. Fig 1. shows the block diagram and front panel of TGDA.
We will discuss two important applications using this TGDA.
(1) Water level Monitoring: Five resistors R1 to R5 are connected in series and the junctions of resistors are extended to the five levels of the water tank using wires. A reference rod is also fitted with its lower end just below level 1. Plug in a dummy resistor of 100k into SOC1 and rotate dial 1 to the zero-resistance position. Adjust dial 2 to read 55 in the display. Cover the unit digit with an opaque tape so that only the ten's digit is visible. Now remove the dummy resistor. Connect the other end of five resitor ladder and the reference probe to SOC1. The display will show the water levels fron one-fifth to five-fifth of the tank depending on the actual level at that time. Fig 2 shows connections for water level monitoring
(2) Plant Monitoring and Tendering:You can use this circuit to indicate the time of watering in order to avoid excessive watering to plants. For this insert two metal strips (rods) on both sides of the plant. Connect them to earphone plug using wires and insert the plug into SOC3. Since soil-resistance increases with loss of water, the alarm can be set/activated for a specific moisture level. Adjust dials 1 and 2 such that the buzzer sounds when the plant needs to be watered. The buzzer stops in a short while on sprinkling water over the soil supporting the plant. Next time the buzzer will sound automatically when the plant needs to be watered. Fig 3 shows connections for plant monitoring and tendering.
Other applications can be measuring unknown resistance and capacitance, testing a diode, rain alarm indication, numbers game, security alarm, fire alarm, strengthness meter. You can use this in a number of ways depending on your innovation, imagination and creativity.