Published:2012-10-30 21:30:00 Author:muriel | Keyword: Buck Converter
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Published:2012-10-29 22:07:00 Author:muriel | Keyword: High Efficiency , 500kHz, 4.5A , Step-Down Converter
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Published:2012-10-29 22:06:00 Author:muriel | Keyword: 60V/3A, Step-Down DC/DC Converter
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Published:2012-10-29 22:03:00 Author:muriel | Keyword: Single Inductor, Tiny Buck-Boost Converter
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Published:2012-10-29 22:02:00 Author:muriel | Keyword: LM2673 , Positive to Negative Converter
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Published:2012-10-29 22:00:00 Author:muriel | Keyword: Micropower Buck/Boost Circuits
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Published:2012-10-29 22:00:00 Author:muriel | Keyword: Micropower Buck/Boost Circuits
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Published:2012-10-29 21:59:00 Author:muriel | Keyword: Single-Cell, Li-Ion Battery , 2.5V Converter
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Published:2012-10-29 21:58:00 Author:muriel | Keyword: 4-Switch , Buck-Boost Converter
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Published:2012-10-29 21:43:00 Author:muriel | Keyword: buffered current source
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Published:2012-10-29 21:39:00 Author:muriel | Keyword: 300V , PEAK TO PEAK , SIGNAL GENERATOR
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Published:2012-10-29 1:43:00 Author:muriel | Keyword: A simple step-up converter, 6V to 12V
This step-up converter is intended for use in a '67 Citroen 2CV. This car, and I use the word loosely, has a 6V battery and won't support a modern radio that needs 12V. The circuit described here converts 6V to 12V at 1A sustained load current.
When the switch is closed an extra current flows through the inductance and stores energy there. The capacitor supplies the load with current during this time.
After the switch closes the capacitor is charged by the energy stored in the inductance and an extra current starts flowing through the load, causing the output voltage to rise (energy is supplied directly from the input source also as long as the diode is forward biased). During this time, the system behaves like a RLC-circuit, so, after a while, the current decreases. The switch is then closed again and the cycle repeats. One could say that charge is pumped from input to output, increasing the output voltage up to the point where there is an equilibrium between the discharging of the capacitor while the switch is closed and the charging by the inductor while the switch is open.
The output voltage equals (ton / toff + 1)ΧUin and is controlled by PWM of the switching action. (View)
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Published:2012-10-29 1:41:00 Author:muriel | Keyword: Two Transistor
It has been interesting analyzing these radios. You have to give the Japanese credit for even making a radio that can drive a speaker with only 2 transistors! Basically, the first transistor (Q1) performs double-duty. It first acts as an RF amplifier, with some of the signal being fed back to the antenna coil to provide some regeneration for better selectivity and sensitivity. (This also results in a non-linear amplification of the signal which results in noticeable distortion.) The RF (radio frequency) signal is then rectified ( detected ) by the diode, and then the resultant audio signal is fed back to the base of the first transistor where it acts as the first AF (audio frequency) amplifier. (This is called a reflex circuit.) The audio signal is then fed through an interstage transformer to Q2 (the second transistor). The transformer provides impedance matching. The second transistor acts as a power amplifier, with the output signal going through an audio output transformer (to provide impedance matching again), and then finally to the speaker. Everything about this circuit is designed to provide maximimum gain; consequently there is no AGC (automatic gain control), and stronger stations come in a lot louder than weaker stations; unlike 6-transistor (or more) radio circuits which have an AGC circuit or function. (View)
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Published:2012-10-29 1:40:00 Author:muriel | Keyword: 12V to 28V, DC-DC Converter, LM2585
This boost regulator is for those times when you have a 28v relay, but want to use it with a 12v source. The circuit is built around the National Semiconductor LM2585, and uses the energy stored in an inductor to boost the 12v to 28. Output voltage can be varied by adjusting the ratio of resistor values on the feedback pin. (View)
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Published:2012-10-25 21:38:00 Author:muriel | Keyword: 12v battery monitor
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Published:2012-10-25 21:37:00 Author:muriel | Keyword: Battery Discharge Monitor
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Published:2012-10-25 21:37:00 Author:muriel | Keyword: Battery Charge, Current Indicator circuits
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Published:2012-10-25 21:36:00 Author:muriel | Keyword: Alkaline, Low Battery Voltage , Indicator
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Published:2012-10-25 21:34:00 Author:muriel | Keyword: 9v , Battery Voltage Monitor
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Published:2012-10-25 21:32:00 Author:muriel | Keyword: BattMan II, Computer Controlled, Battery Manager
BattMan II consists of five subsystems: power supply, current control, battery connection, voltage measurement, and logic power.
The power supply I used is a commercial off-the-shelf model that can supply 18 Volts at 2.2 Amps. I purchased mine at a surplus store. Any similar power supply will do, so long as it produces 18 to 20 Volts, and enough current for the maximum charge rate you want to be able to use. Points labeled V+ in the schematic are connected to the positive terminal of the power supply.
CMOS buffers Z2a through Z2d together with resistors R26 through R34 form an R-2R ladder digital-to-analog converter. R34 is used to adjust the output voltage range so that it spans 0 to 0.2 Volts (which can be measured at test point TP2). The input to the converter is taken from the four low-order data bits (D0 to D3) of the parallel printer port that BattMan is connected to. (View)
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