Forgot the password?
The largest Electronic Circuits Database on the Net
Meter Counter Circuits
This design is for an external signal strength meter that is analog, digital, and audible for mobile transmitter hunters. The S meter also incorporates a gain circuit. The digital LED bar graph display has a very fast response time. The 3.3-KO resistor near LM3914 can be replaced with a 5-K pot to control LED brightness. The S2A position gives a 2:1 gain and the S2B position gives about a...
The 5-MHz track and hold shown here has a 400-kHz power bandwidth driving Â±10 V. A buffered input follower drives the hold capacitor, C4, through Ql, a low resistance FET switch. The positive hold conuuand is supplied by TTL logic, with Q3Ievel shifting to the switch driver, Q2. The output is buffered by A3. When the gate is driven to V-for hold, it pulls the charge out of the hold...
Channel 1 is wired as a voltage follower and is turned on during the track/sample time. Ifthe product of R x Cis sufficiently short compared to the period of maximum output frequency, or sample time; Cwill charge to the output level.
A standard shaft encoder"s A and B ports generate square waves with the same frequency as the shaft turns. The phase of A will lead or lag that of B by 90Â°, ~depending on the direction of rotation. To obtain maximum resolution, the tachometer circuit must count every change of the state for the A and B signals. Each such change causes a change of state at IC1A"s output, followed by a 1-!LS...
Using Linear Technology LT1027 reference and LT1078 op amps, transducer T1 is fed with 1.5 mA. The pressure transducer f
Capacitor Esr Measurer
The equivalent series resistance (ESR) of a capacitor can be measured using this circuit and an ac voltmeter. Ul fun
Harmonic Distortion Analyzer Circuit
The circuit includes a low-distortion, 1-kHz oscillator and will measure THD at a user selected voltage level for voltage amplifiers, or for checking amplifiers of power levels to 600 W. It will detect THD levels of .005% (-86 dB). A built-in one-percent THD calibrator is included.
Here is a simple tachometer circuit for use with a hand-held DVM or portable chart recorder. A novel feature is that the source frequency pulse/rev rate can be directly set on a ten-turn potentiometer to provide a convenient calibration of one V per 1000 rev/min. This is particularly useful when measuring a shaft or engine speed by sensing gear teeth.
Four-Trace Oscilloscope Adapter
This simple adapter uses an oscillator (567) to drive a counter (U2) and switch (U3) that selects the outpu
Digital Tachometer Counter
This circuit produces a readout for the digital tachometer circuit. IC9 is a 3-digit LED display driver, counter
Ac Watts Calculator Circuit
The load`s power factor, which is the cosine of the phase angle between the voltage across the load current, can be calculated simply with this circuit. A1:1 isolation transformer is used to prevent direct contact with the line. By properly adjusting Rr, the vector diagram of voltages Vs, Vd, and Vr forms an isosceles triangle, which simplifies the power calculation. The method basically...
Buzz box continuity and coil checker
Differences between shorts, coils, and a few ohms of resitance
A very sensitive pico ammeter (â€” 1 V/pA) employs the amplifier in the inverting or current summing mode. Care must be taken to eliminate stray currents from flowing into the current summing mode. It takes approximately 5 for the circuit to stabilize to within 1% of its final output voltage after a step function of input current has been applied
This tachometer lets you measure heartbeats, respiratory rates, and other low-frequency events that recur at intervals of 0.33 to 40.96 seconds. The circuit senses the period offm, computes the equivalent pulses per minute, and updates the LCD accordingly. Although the decimal readout equals 60 fm, the circuit doesn"t actually produce a frequency of 60 fm.
Simple Absolute Value Circuit
When an input voltage is positive, the output of ICA is negative and diode D does not conduct; hence the outp
Thermally based anemometer
This design used to measure air or gas flow works by measuring the energy required to maintain a heated resistance wire at constant temperature. The positive temperature coefficient of a small lamp, in combination with its ready availability, makes it a good sensor. A type 328 lamp is modified for this circuit by removing its glass envelope. The lamp is placed in a bridge which is monitored by...
The circuit uses the exceptionally low input current (O.lpA) of the CA3420 BiMOS op amp. With only a single 10 megohm resistor, the circuit covers the range from Â±50 pA maximum to a full-scale sensitivity of Â±1.5 pA.
Bandswitched Grid Dip Meter
For checking resonances, tuned circuits, antennas, etc., this circuit covers the 2-to 20-MHz range. Ql serves a
Ammeter with six decade range II
The Ammeter measures currents from 100 pA to 100 Âµ without the use of expensive high value resistors.
Rf power meter
Reflectometer (SWR Power Meter) covers three decadesâ€”from 100 kHz to 100 MHz
Digital Vom Phase Meter
The phase-angle meter will work with either analog or digital inputs. A DVM is used as a readout device. The output
This circuit is designed around a 4049 hex inverter/buffer. Two inverters are used ina dual-frequency signal-injector circuit, another inverter is used as a logic probe, and the remaining three inverters are used as a sensitive dual-input, audio-signal tracer. The signal-injector portion gates are configured as a two-frequency, pulse-generator circuit. Under normal conditions, the...
Zero center indicator for FM receivers
To adjust, tune in a station and adjust the I"M pot for a null. Then ask the station to modulate and fine adjust so modulation peaks don"t light the LEDs
This circuit has a linear reading scale, requires no calibration, and requires no zero adjustment
Field strength meter 1-150Mhz
The tuning range is determined by coil (L) dimensions and setting of Cl. Coils can be plugged in for multirange use or soldered in place if only limited frequency range is of interest. Cl = 36 pF variable, C2 = 047 disc, D = 1N60 (germanium) and M=0-1 mA meter
Simple Spectrum Analyzer Adaptor For Scopes Circuit
Suitable for monitoring an amateur band or a segment of the radio spectrum, this simple adaptor uses an NE602 mixer-oscillator chip to produce a 455-kHz IF signal, which U2 amplifies, then feeds to detector D2 and the Y axis of an oscilloscope. VT is used to drive the horizontal axis input of a scope. L2 and L3 are coils suitable for the frequency range in use. For this circuit, coils are...
Adjustable-sensitivity field-strength indicator
The LED lights if the rf field is higher than the pre-set field strength level. Diodes should be germanium
Adjustable audible continuity tester
The tester gives an audible indication, making it unnecessary for the user to look directly at the instrument to observe a meter reading. In addition, the current and voltage of the tester are strictly limited. It can apply no more than 0.6 volts dc and no more than 3 mA through the probes. It can therefore be used safely on circuit boards in which semiconductor components have been installed,...
This circuit reads and stores voltages, tbus freezing the meter reading even after tbe probes are removed. The op amp is configured as a unitygain voltage follower, witb C1 situated at tbe input to store tbe voltage. For better performance, use an LF13741 or a TL081 op amp in place of tbe 741.
Low cost ph meter
With guaranteed 1 pA input bias, the ICL 8007A is ideal as a pH meter
Peak detect and hold
If the voltage at the input exceeds the voltage on the capacitor, then the output of the 741 goes positive, the diode conducts, and the capacitor is charged up to the input voltage-forward voltage drop of diode. When the voltage at the input is less than that on the capacitor, the output of the 741 goes negative, and the diode cuts off
Two important properties of the 8043 are used to advantage in this circuit. The low input bias currents give rise to slow output decay rates (droop) in the hold mode, while the high slew rate at 6 V/p,s improves the tracking speed and the response time of the circuit. The upper waveform is the input 10 V/div, the lower waveform the output 5 V /div. The logic input is high.