Free electronic circuit design and schematic diagram
If we want to record very low frequency or DC signal on an audio recording system, we have to convert the DC/low frequency signal into the spectrum of audible sound. The figure of DC response data recording system is shown below. We can record low-frequency analog data (DC to 10kHz) anywhere, store, and then reproduced. The frequency spectrum of the […]
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This is a Voltage Controlled Oscillator (VCO) circuit. This circuit is based on Hartley oscillator. The frequency depend on the value of C1 and L1. The oscillation-frequency will change as the change of the capacitance in the varactor BB132 by The Vtuning voltage. The maximum frequency that can be changed is determined by th value of C2. For large frequency […]
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It is advantageous to convert the analog signal into a digital signal, which is less susceptible to noise pick-up when transmitting analog data over long distances. It is very easy for noise to interfere the amplitude of a signal, but it would be harder to change its frequency. The TC9400 converts the input voltage into a pulse or square wave […]
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The TC9400 converts the analog input (Vin) ito frequencies (10Hz to 100KHz) which can be used to modulate an RF transmitter in a telemetry system. At the other end, The RF signal is picked up by receiver and it’s demodulated back into the 10Hz to 100KHz spectrum. A count linearly proportional to the original analog voltage (Vin) is given by […]
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Telephone line is designed to carry audio signal, which is an alternating current in nature. To transmit measurement signal, which has very low frequency or DC signal, we have to convert the signal into AC with acceptable frequency range for telephone line transmission. For transmitting analog data over telephone lines, its ideal to use the TC9400’s square-wave output. Since the […]
Read moreTurning long term integrator into bipolar input introduce a concept similar to “negative frequency”, where the counter would react to decrement its counter when a negative frequency is supplied. Off course there’s no such concept in reality, but we can achieve the same function by rectifying the input before converted to frequency, and detecting the polarity to control the up-down […]
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Measuring charge amount in electroplating, or measuring actual battery capacity can be done with integrator. Special requirement for this integrator is that it should has no leakage for long term operation, ranging for hours to several days. Using a voltage-to-frequency converter and a counter can solve this problem, here is the block diagram of the system: The counting values is […]
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