This current to voltage converter rely on the very high input impedance of the operational amplifier. The input current (I) is forced through feedback resistor (Rf), and generates an output voltage equal to (-I x Rf). This output voltage is valid for output voltages from rail to rail, namely from -5 to +5 volts in this example.
This current to voltage converter rely on the very high input impedance of the operational amplifier. The input current (I) is forced through feedback resistor (Rf), and generates an output voltage equal to (-I x Rf).
The circuit in Figure 1 is a simple, low-cost voltage-to-time converter using the ubiquitous 555 timer chip. You can use the IC`s monostable multivibrator as a voltage-to-time converter by connecting the analog-voltage input to the charging resistor, R, instead of connecting R to VCC. With this modification, the timer chip`s output-timing cycle, tP, is proportional to the input voltage, VIN.
The circuit in Figure 1 converts
pulse information to a clean dc voltage
by the end of a single incoming
pulse. In another technique, an RC filter
can convert a PWM signal to an averaged
dc voltage, but this method is slow in responding.
pulse information is slower yet.
This circuit is intended to provide good square waves converting a sine wave picked-up from an existing generator. Its main feature consists in the fact that no power-source is needed: thus it can be simply connected between a sine wave generator and the device under test.
Figure 1 shows the typical output from a spectroscopic amplifier, where the presence of a large amount of detector noise with Gaussian distribution is a limiting factor for system performance in amplitude and timing resolution. The time-tagging of such pulses is subject to two well-known types of errors: the jitter related to the noise and the "walking time" arising from the amplitude variation of the signals.
This Circuit is a zero crossing detector, which produces an output state change whenever the input crosses the reference input. In this case the reference input is connected to ground. The output of the comparator can easily drive multiple outputs, which can include, for example, a relay, acontrol gate and a LED indicator.
Figure 1 shows a classic voltage-to-current (V/I) converter. You can select the resistor values such that the output current in the load, RL, varies only with the input voltage, VIN, and is independent of RL. The circuit is widely used in industrial instruments for supplying a 4- to 20-mA signal. The circuit has its limitations, however, because the resistor values must be quite accurate to obtain a true current source.
The voltage-to-current converter in Figure 1 can both source and sink current. The circuit is more flexible than some traditional current references that require different topologies for current sourcing and sinking. Also, you can easily adjust the value of the current reference by simply adjusting the circuit`s input voltage.
The voltage-to-current (V/I) converter in Figure 1 uses three common op amps, two medium-power transistors, and only a few passive components. The first op amp (IC1) inverts the sum of voltages VIN and VOUT to V1=-(VIN+VOUT). The second op amp (IC2) and transistors Q1 and Q2 invert this voltage to produce VIN+VOUT.
The circuit in Figure 1 performs active voltage-to-current conversion or acts as a variable-gain current mirror with high precision and bandwidth. A typical application is testing high-speed ICs or other devices that have inputs designed to be driven from current-steering DACs to enable a modulated voltage source to control the devices. The circuit thus simplifies the testing of such devices in isolation, because modulated voltage sources are...
Single-phase induction motors are extensively used in appliances and industrial controls. The Permanent Split Capacitor (PSC) single-phase induction motor is the simplest and most widely used motor of this type. The classification, construction and working principle of single-phase induction motors are explained in detail in the application note "AC Induction Motor Fundamentals" (AN887) available from Microchip.
The inspiration for the VCO
in Figure 1 came from Texas Instruments
application notes of years ago, detailing
the use of unbuffered U-type inverters
for use in ring oscillators. The
application notes circuit consists of only
the inverters. The circuit generates relatively
squarish waveforms. Any ring oscillators
operation depends on the fact
that an odd number of
inversions exists around
The circuit in Figure 1 is a quadrature-output VCO that provides both positive and negative output frequencies, depending on the polarity of the control-voltage input. The circuit provides a function that designers traditionally implement in analog music-effects units, such as Bode/Moog frequency shifters. Bode/Moog shifters use fixed-beat-frequency oscillators at 20 kHz and variable sine oscillators that go higher and lower than 20 kHz. Both...
This circuit is used to convert a mono audio signal into a stereo signal that can be panned between the left and right channel by a 0-10V control signal, it is intended for analog synthesizer systems. The circuit is mainly here for historical reasons, a higher quality panner may be built with the National Semiconductor LM13700 dual transconductance amplifier set up as a pair of voltage controlled amplifiers.
A VCO (voltage-controlled oscillator) is an analog circuit, so you cannot find it in the libraries for the design of digital programmable chips. When you need such a circuit for synchronization or clock multiplication, you need to find a circuit that works with the standard digital functions, such as AND and NAND. Several possibilities exist for building variable-frequency oscillators. For example, you can change the frequency using a varactor...
This is a 0 - 6 MHz DDS VFO controlled by a PIC16F84 (or `C84).
The VFO is separated into two modules, the DDS module and
the controller module. The PCB layout (double sided) for
the DDS module is included as two Postscript files
(scale 1:1). The .PS files can be copied to a Postscript
capable printer such as HP LaserJet 4MP. Please note that
the layout is mirrored to get the toner side of the film
toward the PCB surface.
The circuit is also an inexpensive VCO (voltage-controlled oscillator) with only five components. Many types of ceramic capacitors for surface-mount placement are on the market. The parts become continually smaller because of space problems on the board, and the capacitance values continually increase to compete with more expensive tantalum-electrolytic units. Unfortunately, capacitors with X5R, Z5U, or Y5V dielectrics have some undesirable...
The basic VFC (voltage-to-frequency converter) in Figure 1 comprises an integrator (IC1) and a Schmitt-trigger circuit (IC2). The integrator converts the dc input voltage, VIN, to a linear voltage ramp, and the Schmitt trigger sets the limits of the integrator`s output voltage. Feedback around both circuits provides the condition for oscillation. The DPP (digitally programmable potentiometer) in Figure 2 adds programmable limits to the Schmitt...
The output cable from my 20 MHz function/sweep generator dangled over the side of the workbench, the alligator clip hovering over the floor. Deeply engrossed in a project, I moved the power strip on the floor a little closer so I could plug in the circuit upon which I was working. That's when the alligator clip contacted the 240 VAC. The function/sweep generator had been gravely injured. Poking around with a scope probe, the signal output was...
This circuit is an oscillator at frequency 10MHZ, using IC 1A and IC1B and a frequency divider. Using the IC2 it divides the pulses to 10. IC1C is a buffer. The variable capacitor 39pF is microtunig the frequency . The pin 12 of the IC2 is the output, where we can have the 1 MHz . The circuit does not need any adjustments to work.
This project is a digital Automatic Gain Control (AGC”) system using a PIC16F876 MCU. The ability to set the gain level in a circuit and have it control itself is a very useful function. This circuit is a building block of another project I am working on. A 30W power amp for either the PCS, iDEN or CDMA frequency bands. I will settle on one of those frequencies sometime soon. I needed to control the gain so the signals for a digital...
This converter allows reception of signals below 500 kHz on a 3.5 ? 4 MHz HF receiver. It should therefore be useful for those with receivers that do not receive the lower frequencies. Again the converter uses the popular NE602 mixer/oscillator chip. A cheap 4 MHz crystal provides the local oscillator tuning. Note that tuning is backwards ? 100 kHz corresponds with 3.9 MHz and 500 kHz with 3.5 MHz. If your receiver tunes above 4 MHz, the 4 ?...
In some cases of temperature measurements, it is more advantageous to convert the measured value into a frequency than into a voltage. A temperature to frequency converter can be directly connected to a frequency counter or it can be connected to a computer without using any A/D interface to display the measured value. The conversion factor of the