Circuits & Schematics: metal detector

1. How to build an isolated digital AC dimmer using Arduino
   Circuits Arduino Supply NXP BT138-800
   .. it is used to attach a heatsink) is connected to the Pin-2. It means you should never touch the heatsink or screw it to a metal enclosure! R4, R5, and C2 implement a snubber circuit [1] for the IC2 and C1 and R7 make a snubber circuit [ 1 ...
   .. points (the points where the wave changes its polarity) are important. To grab these points, we have to use a zero crossing detector. The Figure 2 demonstrates the schematic diagram of the whole circuit. Figure 2. Schematic diagram of the ...
   26-04-2024

2. How to make a noise-free infrared obstacle detection module
   Circuits Measurement Robots Vishay TSOP1738KA1
   .. of the sensor to detect the obstacles located near or far from the sensor. Figure 1. Schematic diagram of the IR obstacle detector. According to the TSOP1738 datasheet: “The TSOP17XX series are miniaturized receivers for infrared ...
   17-04-2024

3. Single phase mains cycle skipping controller sans harmonics
   Circuits Supply Diodes NE555
   .. an adjustable width within 200 ms, by adjusting potentiometer RV1. This pulse train controls an optotriac with zero cross detector U2 ( MOC3033 ) to trigger triac U1 ( BTA25-600BW ). The triac conducts for the duration of “off ...
   15-04-2024
4. Rotary encoder mates with digital potentiometer
   Circuits Digital Switch Channel RE11
   .. electrical encoder, in which each turn can create some bounce or noise issues because of the imperfect nature of the metal contacts within the switch. The LS7084 prevents such erroneous signals from reaching the AD5220 . The operation ...
   29-03-2024
5. Supersized log-scale audio meter
   Circuits Audio Measurement Texas Instruments TL084 LM385
   .. is a logarithmically-squashed version of the input. For now, we only need its positive peaks. A2 and Q1 form a simple peak detector. Whenever A1.OUT is greater than the voltage on C2, A2/Q1 dumps current into C2 until the voltages match. ...
   21-03-2024
6. High-power LED drivers require no external switches
   Circuits Supply Light Maxim MAX1685 MAX4162 MAX5035
   .. 2, and figure 3 are suitable for applications in which the power source comprises three or four alkaline, NiMH (nickel-metal-hydride), or NiCd (nickel-cadmium) cells. Those in figure 4 and figure 5 are for vehicular applications in ...
   20-03-2024
7. Voltage inverter uses gate's output pins as inputs and its ground pin as output
   Circuits Supply Texas Instruments SN74AC14 CD40106B
   .. as inputs and ground as an output was fun. And an afterthought: For higher voltage operation, simply drop in CD40106B metal-gate chips for the 74AC14s, then with no other changes, V+ and V- can be as high as 20 V. Materials on the ...
   13-03-2024
8. ∆Vbe differential thermometer needs no calibration
   Circuits Analogue Design Measurement Texas Instruments CD4053B TLV2374
   .. convenience, the R5/R6 ratio was chosen so that Resistor values adorned with an asterisk in the schematic denote precision metal-film types. Current-ratio-setting R2, R3, R13, and R14 are particularly critical to minimizing zero error and ...
   06-03-2024
9. Direction detector doubles as decoder
   Circuits Measurement Beginners Digital Texas Instruments CD4093B
   Fig 1’s circuit, which was developed to monitor the traffic of bumblebees into and out of the hive, differentiates “a-to-b” motion from “b-to-a” motion. When used with an optical decoder, the circuit distinguishes ...
   01-02-2024
10. Simple log-scale audio meter
    Circuits Audio Measurement Texas Instruments TL081
    .. sketched in Figure 1, shows the first pass at the idea, and avoids those disadvantages. Figure 1. This basic peak log detector shows the principals involved and helps to highlight the problems. (Assume split, non-critical supply ...
    22-01-2024

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