Free electronic circuit design and schematic diagram
Microphone can’t be directly connected to a power amplifier because the signal is too weak. Standard audio power amplifier accept about 1 Vrms to give a full volume (maximum power), and off course there’s such microphone has such high level output. To provide signal with high enough amplitude, we can use a pre-amplifier circuit shown in the schematic diagram below: […]
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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The voltage that control a V/F converters will be displayed if we use a frequency counter, which is directly proportional to the input voltage. A 1 second time base will give 4 digit resolution with 1 reading per second when the V/F converters is running at 10KHz full scale. To transmit the frequency, we can use the optoisolator, so there […]
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Voltage step-up also employed in figure below, but for a different purpose. The common requirements are transmission of industry standard 4-20mA current loop signals to valves and other actuators. Current transmitters is required by resistive line losses and actuator impedance to be able to force a compliance voltage of at least 20V. 5V powered systems usually cannot meet current […]
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Door intercom is very useful for home security. If you receive a door knock or door bell/alarm, you can push this intercom knob and ask the guest to identify his/her self, before deciding to open the door to welcome. Here is the schematic diagram of the circuit: To install this door intercom, except for right side speaker, you should place […]
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We can use a circuit breakers to limit the current in a single circuit in most household applications. Although breakers come in many sizes, typically a single circuit is limited to 20 amperes. This means that to bend it downward and release the spring-loaded trip-lever, 20 amps of current will heat the bimetallic strip. Another mechanism is employed to handle […]
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