AM Radio Receiver Circuit Employs FM IC Chip
This AM receiver consists of a TDA7000 single-chip FM receiver (U1) as the main radio component, and an LM386 chip for low-voltage audio-power amplifier (U2) circuit. The receiving coils are hand-wound coils (L1 and L2), and a few additional components. This coils, together with the variable capacitor, is chosen to match the AM frequency. To …[Read More]
Power Saver for Relays
Relays are normally operated at current level where it can initiate the mechanical metal contactors movement. After contacts has been established, the current level needed to keep the conductor plates stay attached is actually smaller than the current to initiate it. This power saver circuit seems to have opposite mechanism of surge protector. This circuit …[Read More]
This doorbell circuit produces a low tone that will slide up to higher frequency. The equivalent total resistance connected between the base of Q1 and ground (Rbg) , and coupling capacitor C1 determines the AF oscillator’s frequency. The resistance (Rbg) is equal to (R2+R1)R3. Here is the schematic diagram of the circuit: The R2 is …[Read More]
True Stereo Indicator Detects L-R Signal Difference
This true stereo indicator is different from what we usually find on FM radio receiver, which is usually a pilot tone detector. A stereo broadcast from FM radio station contain pilot tone, but a presence of pilot tone doesn’t necessarily a stereo broadcast signal since a mono FM transmitter ca broadcast pilot tone as well. …[Read More]
One Direction Motion Sensor
This is a one direction motion sensor circuit. This motion sensor circuit is used to detects an object passing in one direction, ignoring an object that going to opposite way. This circuit uses two sensors to identify the movement only in one direction. The basic principle of this circuit is simple, where one sensor is …[Read More]
53 dB Stereo Preamp for Tape or Phonographs
With the circuit shown in the following schematic diagram, both channels of this stereo preamp is constructed using RCA CA3052 quad AC amplifier. this pre-amplifier circuit is featured with tone control (bass – treble). Make a similar circuit to complete the other channel, since the circuit for left and right channel are similar. To be …[Read More]
Strobed Supply Improves Strain Gauge Bridge Efficiency
The following schematic diagram shows a method to reduce power consumption without sacrificing the bridge signal output level of a strain gauge. Many situation will be applicable for this strain gauge bridge signal conditioning circuit, where continuous output is not a must. In the long time frame, this circuit will in idle state for almost …[Read More]
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