Digital Bike Tachometer Wiring diagram Schematic

This is the simple tachometer for bikes uses 2 reed switches to urge the speed data of the bicycle. The reed switches are put in close to the rim of the wheel where permanent magnets pass by. The permanent magnets are connected to the wheelspokes and activate the reed switches everytime they pass by it. The speed is digitally displayed.

The tachometer schema works in step with this principle; the pulses created by the reed contacts are counted inside an explicit time interval. The ensuing count is then displayed and represents the speed of the bike. 2 4026 ICs are used to count the pulses, decode the counter and management 2 7-segment LED show. RS flip-flops U3 and U4 perform as anti-bounce.

Electronic bicycle SP tachometer schema diagram

The pulses arrive at the counter’s input through gate U7. The measuring amount is set by monostable multivibrator U5/U6 and might be adjusted through potentiometer P1 so the tacho are often calibrated. The schema U1/U2 resets the counters.

Since batteries are used to power the schema, its not sensible to support the continual show of speed data. This schema isnt continuously active. The schema is activated solely once a button is pressed. a minimum of 3 permanent magnets should be put in on the wheel. The schema are often calibrated with the assistance of another pre-calibrated tachometer.

Streampowers

Voice Bandwidth Filter Wiring diagram Schematic

This schema passes frequencies in the 300Hz - 3.1kHz range, as present in human speech. The schema consists of cascaded high-pass and low-pass filters, which together form a complete band-pass filter. One half of a TL072 dual op amp (IC1a) together with two capacitors and two resistors make up a second-order Sallen-Key high-pass filter. With the values shown, the cut-off frequency (3dB point) is around 300Hz. As the op amp is powered from a single supply rail, two 10kO resistors and a 10µF decoupling capacitor are used to bias the input (pin 5) to one-half supply rail voltage.

Circuit diagram:

 Voice Bandwidth Filter Circuit Diagram

The output of IC1a is fed into the second half of the op amp (IC1b), also configured as a Sallen-Key filter. However, this time a low-pass function is performed, with a cut-off frequency of about 3.1kHz. The filter component values were chosen for Butterworth response characteristics, providing maximum pass-band flatness. Overall voltage gain in the pass-band is unity (0dB), with maximum input signal level before clipping being approximately 3.5V RMS. The 560O resistor at IC1bs output provides short-schema protection.

Source by : Streampowers

Equalising HEXFETs Wiring diagram Schematic

When experimenting with audio output stages featuring multiple HEXFETs it quickly becomes apparent that the total power is not divided equally among the individual transistors. The reason for this lies in the wide part-to-part variations in gate-source voltage, which in the case of the IRFP240 (or IRFP9240) can be from 2 V to 4 V. Source resistors in the region of 0.22 Ω as commonly seen in amplifier diagram (see example schema extract) help to counteract this, but usually not to a sufficient extent. One possible solution to this problem is to ‘select’ the transistors used so that their gate-source voltages match as closely as possible.


For building prototypes or very short production runs this is feasible, but requires additional manual effort in testing the components, and, of course, more transistors must be ordered than will finally be used. The schema idea shown here allows differences in gate-source voltage between pairs of transistors to be compensated for by the addition of trimmer potentiometers: the idea has been tested in simulation using Simetrix. The second schema extract shows the required changes.

Streampowers