Measuring the radiation can be made not only with expensive factory-made instrument. The simplest device (see Figure 1), can be build if you have a counter (radiation detector) type SBM-20 or similar. The circuit is powered by a 220 volts AC 50/60Hz. The double-voltage rectifier circuit is made of diodes VD1, VD2, and capacitors C1, C2. The DC vol
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tage across the capacitors C1 and C2 is about 310 V on each one, so the total voltage of the rectifier is approximately 620 V. The voltage 620 V is divided by a voltage divider to the 400 V. The resistors R5 and R3 forms the voltage divider for the voltage across the capacitor C1, and the resistors R6 and R4 - for the voltage across the capacitor C2. That is why the voltage across the resistors R3 and R4 is about 200 V. Thus, the Geiger-Muller counter BD1 (radiation detector) is powered by 400 V, while the neon lamp HL1 (an indicator) is powered only by 200 V. The neon lamp HL1 is lit only when transistor VT1 is on, and this transistor is on when the radiation ionizes the gas inside the Geiger-Mueller tube BD1. The resistor R1 helps to switch off the transistor VT1 when there is no radiation, and the resistor R2 limits the base current of the transistor VT1 when there is the radiation. When there is no radiation sources around, the Geiger-Muller produces 20. 30 electrical pulses in one minute because of the natural background radiation. Consequently, the transistor VT1 will be open for a short time - the neon lamp HL1 flashes every 2. 3 seconds, but without strict periodicity. When the radiation levels getting higher, the neon lamp HL1 flashes more frequently. This can be verified by bringing to the counter the usual Christmas toy, covered in phosphorus. When the radiation level is very high, the neon lamp HL1 is lit...
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The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
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The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
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In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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