Free electronic circuit design and schematic diagram
A full-wave rectifier circuit that provides the absolute value of input signals up to ±2.5 V even though operated from a single 5 V supply is shown in the schematic diagram below. The amplifier acts as a unity-gain inverter for negative inputs. The op amp output is forced by positive signal to ground. The 1N914 diode becomes reversed-biased and the […]
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The schematic diagram below show us a circuit of a battery-powered voltage reference that draws only 17uA of supply current. Two AA cells can power this reference over 18 months at this level. Drift of the reference is only at 5.5 uV/°C over the industrial temperature range at an output voltage of 1.23 V @25°C. The load regulation is 85 […]
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We can use tone/frequency detector (decoder) to detect the presence of a signal with a certain tone. The output of the circuit will be active if the signal is the same tone with the tone of a series of internal oscillator. LM567 is one of decoder that we can use. The LM567 and LM567C are general purpose tone decoders. Both […]
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The Vc1 increases linearly when the pull-up resistor RA in the monostable circuit is replaced with constant current source, generating a linear ramp. The linear ramp generating circuit and the generated linear ramp waveforms illustration is shown in figures below. Current source is created by PNP transistor Q1 and resistor R1, R2, and Re. Ic= (Vcc-Ve)/Re Ve= Vbe + (R2/(R1+R2))Vcc […]
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This is a Low Cost Universal Battery Charger Circuit. This circuit is used to charge NiCD-NiMH batteries and ideal for car use. This circuit transforms a mains adapter to a charger. It can be used to charge MP3 players, portables, toys cellular phone, video batteries. This circuit also has selectable charge current. To indicate this device is charging, an LED […]
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This motor driver circuit control the charging and power delivery cycles to enable small solar cell to drive dc motor. Here is the schematic diagram of the circuit: You have to make sure that 4700uF cap doesn’t leak, for more information about this solar cell dc motor driver circuit, you can see here.
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This motor driver deliver the power form capacitor to the motor when the capacitor is charged to 1.75V by the solar cell. After powering the motor, capacitor voltage will be discharged and the circuit will cut the capacitor-motor connection when the voltage drops below 1V, allowing the capacitor to be charged to 1.75V again to repeat the cycles. The motor […]
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