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Power Supply Circuits
High voltage supply
A 6 V battery can provide 100-150 Vdc center-tapped at a high internal impedance (not dangerous though it can inflict an unpleasant jolt). A 6.3 V transformer is connected ' 'in reverse'' with a transistor used in a Hartley oscillator configuration. The frequency of operation may be controlled by varying the value of the 10 ohm resistor.
Room Ioniser circuit
This is a voltage multiplier circuit acting as an Ioniser. Its calculated to feed 220V from mains and the output is about 6KV. Caution should take with the circuit as can be dangerous due to mains. You can place a needle at the output 3cm long.
Cold-Cathode Fluorescent-Lamp Supply
For back-lit LCD displays, this supply will drive a lamp. LT1072 drives Ql and Q2, and a sine wave app
Output voltage great enough to jump a l-inch gap can be obtained from a 12-V power source. A 555 timer IC is connected as an astable multivibrator that produces a narrow negative pulse at pin 3. The pulse turns Ql on for the duration of the time period. The collector of Ql is direct-coupled to tbe base of tbe power transistor Q2, turning it on during the same time period.
Simple high-volt supply
A light dimmer, a 1 Âµf capacitor and a 12 V car ignition coil form the simple line powered HV generator. The current in the dimmer is shown in Fig. B. At times tp t2, set by the dimmer switch, the inner triac of the dimmer switches on, and a very high and very fast current pulse charges the capacitor through the primary of the induction coil. Then at a rate of 120 times per second for a 60 Hz...
The regulator delivers 100-V at 100 mA and withstands shorts to ground. Even at 100 V output, the LT317A functions in the normal mode, maintaining 1.2 V between its output and adjustment pin. Under these conditions, the 30-V zener is off and Ql conducts. When an output short occurs, the zener conducts, forcing Q1"s base to 30 V. This causes Q1"s emitter to clamp 2 VnEs below Vz. well within...
Power Supply Monitor /Memory Protector
This circuit detects low-voltage supply conditions, down to 0.6 V. Dl sets the trip point of the cir
This circuit is fed from a 12-V de power supply. The input to the circuit is then amplified to provide a 10,000-Vdc output.
Capacitor Cl is charged to +28 V through Rl and stores energy for firing the squib. A positive pulse of 1 mA applied to the gate of SCR1 will cause it to conduct, discharging Cl into the squib load XI. With the load in the cathode circuit, the cathode rises immediately to + 28 V as soon as the SCR is triggered on. DiodeD1 decouples the gate from the gate trigger source, allowing the gate to...
The output voltage changes approximately linearly up to 20 KV as the input voltage is varied from 0 to 5 V. The oscillator is tuned by a 5-0 potentiometer to peak the output voltage at the frequency of maximum transformer response between 45 and 55 kHz. The feedback voltage is applied through a 100-KO resistor, an op amp, and a comparator to a high-voltage amplifier. A diode and varistors on...
High Voltage Dc Generator Circuit
In the miniature high-voltage dc generator, the input to the circuit, taken from a 12-Vdc power supply, is magnified to provide a 10,000-Vdc output causing a pulsating signal, of opposite polarity, to be induced in Tl`s secondary winding. The pulsating dc output at the secondary winding of Tl (ranging from 800 to 1000 V) is applied to a 10-stage voltage-multiplier circuit, which consists of D1...
HV regulator with foldback current limiting
A TMOS MTM7N45 (Q2) is used as a series pass element in a linear high voltage supply that accepts +275-V unregulated and produces 250 V regulated with foldback current limiting. A 15-V zener, Dlf provides the dc reference for operational amplifier Ul, whose other input is obtained from a fraction of the output voltage. Ul drives Q3, which drives the gate of Q2.
Stepdown transformer T1 drops the incoming line voltage to approximately 48 Vac which is rectified by diode D1; the resultant de charges capacitor C1-through current limiting resistor Rl-to a voltage level preset by R4. When the voltage on R4"s wiper reaches about 8.6 V, Q1 begins to turn on, drawing current through R7 and the base-emitter junction of Q2. Q2 turns on and supplies a...
Ultra high voltage generator
By repetitively charging and discharging a capacitor through the primary of an induction coil with a high voltage, an ultra high emf is induced in the secondary. Switching is performed by the triac, triggered by the disc at times set by Cl and Rl. With a 12 V car ignition coil for example, the length of sparkgap obtained is 12 mm of air for C2 = 0.1 ÂµÂ¥. If the dielectric strength of air is...
A CMOS oscillator (U1A) drives. U1B through U1F, which drives Ql, which generates a 12-Vpp square wave across the primary
Preregulator for power supply
This SCR pre-regulator keeps the filter capacitor Vc, in a variable output power supply, a few volts above the output voltage V0. The benefits include: less heat dissipated by the pass transistor and therefore small heatsink, cooler operation and higher efficiency, especially at low output voltages. Ql, Rl, R2, Dl and D2 form a constant current source for zener Zl, so that the contribution to...
Zener diode increase regulator output
A zener diode in the ground lead of a fixed pnp regulator varies the voltage output of that device without a significant sacrifice in regulation.
The circuit converts a de voltage (V +) to a high-amplitude square wave in the audio-frequency range. The dual timer, IC2, provides an inexpensive alternative to the traditional transformer for providing complementary base drive to the power transistors, Ql and Q2. You can convert a 6 to 12 V battery output, for example, to an ac amplitude, which is limited primarily by the power rating of...
Photomultiplier Supply Circuit
A Cockcroft-Walton voltage multiplier supplies the stepped voltage required for the dynodes of the PMT without the power-wasting voltage- divider resistor
High voltage geiger counter supply
This circuit will generate about 300 volts dcâ€”at a very low current, but enough for a GM tube.
Off-line flyback regulator
This circuit uses a low-cost feedback scheme in which the dc voltage developed from the primary-side control winding is sensed by the UC1842 error amplifier. Load regulation is therefore dependent on the jcoupling between secondary and control windings, and on transformer leakage inductance.
Memory save on power-down
The auxiliary output powers the memory, while the main output powers the system and is connected to the memory store pin. When power goes down, the main output goes low, commanding the memory to store.
13KV High voltage power supply
This high-voltage power supply has an inverter around Q1 that supplies 150-V pulses to the converter of SCR1 and C2. The output of ?2 is a 4.5-kV pulse that is multiplied by the voltage-tripler network (right) to produce 13.5 kV.
One of the control circuit"s triacs selects the tap on main transformer Tl, which provides the proper, preregulated voltage to the secondary regulator. T2 and its associated components comprise the secondary regulator. The ADC 0804, IC1, digitizes a voltage-feedback signal from the secondary regulator"s output. The MC1415 demultiplexer, IC2, decodes the digitizer"s output. IC2, in turn,...
This circuit is basically tbe classic bucking regulator, except it uses a TMOS N-channel power FET for the chopper and creates its own supply for the gate control. Tht unique aspect of this circuit is how it generates a separate supply for the gate circuit, which must be greater than Vvv. When power is applied, C2 charges, through D2, to +12 V. At this time, Q1 is off and the voltage at...
High-Voltage Supply Circuit
This circuit uses a transistor oscillator and a voltage multiplier to charge CIO and CI 1 to a high voltage. When the spark gap breaks down, T2 produces a high-voltage pulse via the capacitance discharge of CIO and Cll into its primary.
40W 120Vac Inverter
This inverter uses a 12.6-V to 120-V transformer to deliver a quasi-sine wave that has the same rms and peak voltage
Photomultiplier Circuit Circuit
This circuit is typical of the way that a photomultiplier tube is used. The circuit shown is ac coupled, but if dc coupling is needed, the capacitor can be omitted and a suitable interfacing method used.
Figure 99-l(a)"s circuit exhibits a high-output impedance as a result of the small effective capacitance of the series-c
90Vrms voltage regulator
The circuit is an open loop rms voltage regulator that will provide 500 watts of power at 90 V rms with good regulation for an input voltage range of 110-130 V rms. With the input voltage applied, capacitor Cl charges until the firing point of Q3 is reached causing it to fire. This turns Q5 on which allows current to flow through the load. As the input voltage increases, the voltage across R10...
High Voltage Power Supply 10kV
Be very carefull with this power supply because uses 220V mains and has 10KV at output.
Hv Power Supply With 9 To 15Vdc Input Circuit
The combination Hartley oscillator/step-up transformer shown in A can generate significant negative high voltage, especially if the voltage output of the transformer
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