A MOSFET is used as a wideband buffer amplifier. T1 is wound on a toroid of approximately /f diameter, with material suitable for frequency (usually 1- to 20-MHz range). The turns ratio should be about 4:1 depending on load impedance. Typically, at 4 MHz, there are 18 turns on the primary,
A charge pump is a simple means of generating a low-power voltage supply of opposite polarity from the main supply. The 74Cl4 IC is a self-oscillating driver for the MOSFET power switch. It produces a pulse width of 6.5 p,s at a repetition frequency of 100 kHz. When the MOSFET device is off, capacitor C is charged to the positive supply. When the power through the MOSFET switches on, C delivers a negative voltage through the series...
In my opinion that is the best buildable high power amplifier out there. Quality of sound is just remarkable. This is a real bomb proof amplifier like the best Valve amps. Power supply circuit is also shown. Now lets see why we are going to use MOSFETS. Thermally, the MOSFET has an advantage over the bi-polar transistor. As a bi-polar transistor heats up in use, the collector current increases due to the positive temperature coefficient of...
Proposed power supply for amplifier 100W v-mosfet [ 1 ] is what appears in the above form. It has separated supply for the various stages of supply, stage for power, stage for control, supply for preamplifier and for stage of protection. Whoever wants it can suppress departments or add a power supply for each channel, separating completely the channels between them. For whoever it does not use the circuit of preamplifier and protection can...
This circuit will be of interest to the radio amateur and anyone posessing two radios, (one of which must be able to transmit i.e. a transceiver). It is a self powered (audio derived) repeater circuit for receiving a signal and re-transmitting it via the other radio. This little circuit can turn two hand-held radios into a makeshift repeater. Any radio will work fine as Radio 1, but Radio 2 must be a Yaesu, or some other type that also goes on...
The 60 Watt linear amplifier is simple all solid state circuit using power mosfet IRF840. The IRF series of power transistors are available in various voltage and power ratings. A single IRF840 can handle maximum power output of 125 watts. Since these transistors are used in inverters and smps they are easily available for around Rs: 20/-. The IRF linear amplifier can be connected to the out put of popular VWN-QRP to get an output of 60 Watts....
As I was developing my IR Extender Circuit, I needed to find a way of measuring the relative intensities of different Infra red light sources. This circuit is the result of my research. I have used a photodiode, SFH2030 as an infra red sensor. A MOSFET opamp, CA3140 is used in the differential mode to amplify the pulses of current from the photodiode. LED1 is an ordinary coloured led which will light when IR radiation is being received.
The I.F. amplifier is similar to the one used in the 80M receiver project . The original design has been modified by putting a couple of LED`s in the source circuit of each Mosfet. The voltage drop across the LED`s keeps the source voltage at about two volts. This results in a much greater AGC range. This arrangement was suggested by N6BIU. Thanks Jim. The I.F. transformer primary has 18 turns, the secondary winding has 4 turns.
The circuit requires only one power-switching device, and you can use an analog or a digital signal to drive the switching device. The circuit also requires only a few components: a diode, a switching transistor or a MOSFET, an inductor or a transformer, and a capacitor. Further, the design`s circuit losses are low, and the switching device experiences minimal stress during operation. Figure 1 shows the basic circuit, and Figure 2...
The circuit shows the method of `mirror` current sensing a MOSFET. A fully conducting MOSFET is resistive and behaves exactly as a resistor. It therefore you limit the voltage across the MOSFET when it is conducting you automatically limit the current flowing through it. In addition the MOSFET``s on resistance has a positive temperature coefficient so as it warms up, keeping the voltage across it limited will automatically reduce the limited...
Generating complementary clock signals in a Spice simulation is an easy task. However, this task gets much harder if you need to introduce some dead time into the signals. This difficulty is especially true when you`re dealing with a variable-pulse-width-modulated switching cycle. In fact, you need to insert a dead-time interval between the switching of any two power devices in series, such as bridge or half-bridge designs that use MOSFETs and...
Figure 1 shows a complete circuit for an emergency lamp that operates from a 12V automotive battery. The xenon flash tube requires a 250V-dc anode voltage and a 4-kV trigger pulse. To generate the 250V dc, IC1, a switching regulator controller, and T1, a standard Versa-PAC transformer, operate in the discontinuous-flyback mode. With this configuration, circuit efficiency is typically 75 to 80%. R1 and IC1`s internal-sense-threshold voltage...
High Quality simple design
No need for a preamplifier Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need.
Sensitive systems, such as those in aircraft, must withstand fault conditions, thereby avoiding component and system damage, because a sensor failure could cause a catastrophic event to occur. A channel protector, comprising two n-channel MOSFETs connected in series with a p-channel MOSFET, can protect sensitive components from voltage transients in the signal path, whether or not the power supplies are present (Figure 1).
Figure 1 presents an alternative to the typical boost power regulator. A buck-converter IC, IC1, generates the higher voltage that the white-light LED needs. An internal buck power stage connects between VIN and PGND, sourcing current to output Pin L. This circuit operates by turning on the high switch, thereby connecting the battery voltage across inductor L1. Once inductor L1 stores sufficient energy, the high-side switch turns off. The...
This deceptively simple sequencer actually pulse width modulates the LEDs as it fades from one LED to the next. Bulbs will last much longer when driven in this gentle manner. Add MOSFETs or transistors to the outputs if you wish to drive bulbs. You can reconfigure the three capacitors from a wye configuration to a delta configuration, or you can remove one of them entirely and the circuit will still function. Use high efficiency LEDs for best...
The circuit`s 90% conversion efficiency offers a distinct power-saving advantage over resistor-limited and linearly regulated designs. It might appear that a series-LED connection is unsuitable for applications in which some (but not all) LEDs must be off. A cell phone, for example, sometimes needs that capability for occasions when the display is off but the keypad remains lit. Or, a PDA might need to play a sound file while maintaining...
In this circuit the switches are power MOSFETs driven
to conduct alternately by windings on a current transformer. The primary of this transformer is driven by the
current in the lamp circuit and operates at the resonant
frequency of L-C.
Unfortunately, the circuit is not self starting and must
be pulsed by the DIAC connected to the gate of the
The new LTC1155 Dual Power MOSFET Driver delivers
12V of gate drive to two N-channel power MOSFETs
when powered from a 5V supply with no external
components required. This ability, coupled with its
micropower current demands and protection features,
makes it an excellent choice for high side switching
applications which previously required more expensive
In many applications, it`s desirable to disable LEDs used for system verification. Many options are available for the disabling function, including manual SPST (single-pole single-throw) switches, enhancement- and depletion-mode MOSFETs, bipolar-junction transistors, and JFETs. The circuit in Figure 1 automatically disables the LEDs when a mechanical housing encloses the circuit card, thereby preventing you from accidentally leaving the LEDs...
The circuit is based on IC1, an LTC1430 PWM controller. The current-limiting feature of the IC operates by sensing the voltage across the high-side MOSFET and compares it with a threshold voltage developed across R3.
The LTC1155, dual micropower MOSFET driver, generates
12V from a 5V rail to fully enhance logic-level Nchannel
switches with no external components required
(see Figure 1). Further, the supply current is typically 85mA
with the switch fully enhanced and 8mA with the LTC1155
in the standby mode (both inputs off).
Like most other ESCs, this one is built up using N-channel Power MOSFET`s because of their good characteristics (low DS resistance). Since this ESC has no reverse, it is not meant to be used in R/C cars or boats if reversed motor run is needed. It is more suitable for R/C airplanes. It has no BEC circuit therefore you must power the receiver and the servos from a different source.
Figure 1 shows a simple, cost-effective way of providing these bias voltages. A step-up regulator, IC1, forms the heart of the circuit. This regulator switches at a constant frequency of 1 MHz and a fixed duty cycle of 70%. IC1 steps up the input voltage to 5V by storing the energy in the inductor when the internal MOSFET, M1, is on and transferring this energy to C1 when M1 is off. IC1`s hysteretic gated-oscillator control scheme achieves the...
The circuit in Figure 1 can intelligently control ac or dc current when connected in series with a load. The circuit "steals" its power by turning off the load at a low duty cycle. The switch uses the MOSFETs` parasitic body diode to its advantage. While the MOSFETs are off, the body diodes, along with D1 and D2, serve as two legs of a diode bridge. Current flows through the load and the bridge, charging C1 to the peak ac or dc voltage.
When you need to quickly connect a negative power supply under logic control, the negative power-side switch in Figure 1 can help. Although originally intended for driving the gates of high-current MOSFETs, the MIC4451 can assume a different role. It provides complementary, low-on-resistance MOSFET switches to connect a system power-supply rail to a negative input voltage or to ground, enabled by a digital signal.