Vacuum Tubes Valves
Musical & effects
Yagi Uda Antennas
Metal Detector Circuits
Liquid Sensing Circuits
Light Sensing Circuits
Voltage Detector Circuits
Air-Gas Detection Circuits
Human Sensing Circuits
RF & Radiation
Optical Sensing Circuits
Free Energy Circuits
AC to DC & DC to DC
Solar Cell Circuits
Micro Power Circuits
Switching Power Supplies
Light Laser LED
Digital to Analog
Analog to Digital
Data Bus Circuits
Voltage to Pulse
Current to Voltage
Frequency to Voltage
RF Converter Circuits
Sine to Square Wave
Voltage to Current
voltage to frequency
Period to Voltage
Video Wall circuits
TV Video Circuits
Motor Control Circuits
8051 / 8052
PCB CAD Software
Car bike Circuits
555 Timer Circuits
Remote Control Toy
H Bridge Circuit
DIY HV Variable Cap
DIY PMA alternator
Interconnection & Timing
Digital Signal Integrity
Digital & Bipolars
Sensors & Detectors
Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
Meter Counter Circuits
A continuity tester that has an audible indicator can be more useful in some cases than a visual indicator, because you n
Bandswitched Grid Dip Meter
For checking resonances, tuned circuits, antennas, etc., this circuit covers the 2-to 20-MHz range. Ql serves a
Tuned Rf Wavemeter
Ll and L2 form a tuned transformer. About a 1:3 turns ratio is optimum. L2 and CI tune to the desired frequency. The fre
Remote Field Strength Meter Circuit
This field strength meter consists of a tuned crystal detector producing a dc output voltage from a transmitted signal. The dc voltage is used to shift the frequency of a transmitter of 100-mW power operating at 1650 kHz. The frequency shift is proportional to the received field strength.
Simple Amplified Field Strength Meter Circuit
This circuit uses a FET as a dc amplifier in a bridge circuit. R4 is set for meter null with J1 short circuited. Any surplus 50-mA meter can serve in this circuit. RFC1 is any suitable RF choke for the band in use. A 2.5-mH RF choke will do for broadband operation. R1 is a sensitivity control.
Energy Consumption Monitor Circuit
The ECM circuit consists of four sections, as shown in the block diagram. A power converter generates a voltage that is proportional to the true of real power consumed by the load. That voltage feeds both a bargraph and a voltage-to-pulse converter. The bargraph gives an approximate indication of the amount of power used, and the...
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.
Digital Altimeter Circuit
A pressure sensor (IC4) is used with a dc: amplifier to convert the bridge output (IC4) to a single-ended voltage. ICld provides a reference voltage for setting barometric pressure. IC3 is an A/D converter manufactured by Intersil. This drives an LCD module. Calibration reads out in fact.
Electronic Scale Circuit
An electronic scale using a pressure transducer (load cell) and an analog-digital (A/D) converter to drive a digital display is shown. The scale range depends on load cell. Display is calibrated in appropriate units. Components are on main circuit and display boards. The off-board controls are on the front panel and case.
Radar Calibrator Circuit
This circuit is basically a system that generates a pulsed modulation signal for a Gunn diode microwave oscillator. Several speed settings are preset (S3 a and b). A 555 timer is used with a frequency divider chain to produce Doppler shift equivalents of 25, 35, and 55 rnph,
Simple Curve Tracer Circuit
Useful for checking diodes, transistors, triacs, SCRs, resistors, and LEDs, this curve tracer should prove useful in the experimenter`s lab. It displays the volt-ampere characteristic of a two-ter-minal device on an oscilloscope. This is a simple block diagram of the EZ-Curve.
Light Meter Circuit
The outputs from the comparators will swing, in sequence, from high to low as the input voltage rises above the reference voltage applied to each comparator. The output LEDs will then switch on in sequence as the voltage rises. The inverting inputs of the comparators are connected in common to the collector of photo-transistor Ql. When Ql is...
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...
Fast Video Signal Amplitude Measurer Circuit
Video-signal amplitude can be measured with this simple circuit, which is basically a modified standard peak detector. The device can verify RGB generated by video RAMDACs. Ul is a high-speed buffer and U2 is a latched comparator. CI is a hold capacitor. Reset is performed by Q3. U2 has a latch that maintains the last comparator state. The...
S Meter For Communications Receivers Circuit
Because many amateur receivers are fitted with an S meter that functions far from logarithmically, the proposed circuit should be a welcome extension of such receivers. Although ICs such as the CA3089 or the CA3189 are not in common use anymore, they serve a useful purpose in the meter circuit, because, apart from a symmetric limiter, a...
1Khz Harmonic Distortion Meter Circuit
The circuit useful for distortion measurements notches out the fundamental frequency of 1 kHz to allow measurement of the residual level of harmonics. First a true RMS meter is used to measure the 1-kHz input level E^ by setting SA to the input position. Then, SA is placed in the distortion position and the 2 k potentiometer is adjusted for a...
Ratiometric resistance measurement
The unknown resistance is put in series with a known standard and a current passed through the pair. The voltage developed across the unknown is applied to the input and the voltage across the known resistor applied to the reference input
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...
Electrometer amplifier with overload protection
The preamplifier is protected from excessive input signals of either polarity by the 2N5909 junction field-effect transistor. A nulling circuit makes it possible to set the preamplifier output voltage to zero at a fixed low level (up to + 10~8A) of the input current. (This level is called the standing current and corresponds to the zero-signal...
Guarded input picoammeter circuit
The circuit utilizes CA3160 and CA3140 BiMOS op amps to provide a full-scale meter deflection of Â± 3 pA. The CA3140 serves as an 1T0 gain stage to provide the required plus and minus output swing for the meter and feedback network.
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.
The circuit consists of two basic circuits, the oscillator and the detector. The oscillator uses an FET in a Colpitts configuration. The energy circulating in the oscillator tank is coupled through C4 to the detector circuit, where a small diode (D2) rectifies it, feeding a dc voltage to the Darlington pair (Q2, A3) controlled by the sensitivity...
The circuit uses two general-purpose npn transistors, Ql and Q2, and a special hand-wound, dual-coil probe ferrets out the magnetism. Ql and its associated components form a simple VLF oscillator circuit, with LI, C2, and C3 setting the frequency. The VLF signal received by the pickup coil, L2, is passed through C5 and rectified by diodes Dl and...
Single chip checks resistance
A simple tester can be used for routine checks for resistance on production lines of relays, coils, or similar components where frequent changes in resistance to be tested are not required. The tester is built around a single quad op amp chip, the LM324. R, which is chosen to be around 80 times the resistance to be checked, and the 5 V supply...
Simple continuity tester
The pitch of the tone is dependent upon the resistance under test. The tester will respond to resistance of hundreds of kilohms, yet it is possible to distinguish differences of just a few tens of ohms in low-resistance circuits. Ql and Q2 form a multivibrator, the frequency of which is influenced by the resistance between the test points.
Differential capacitance measurement
A bubble vial with external aluminum-foil electrodes is the sensing element for a simple indicating tiltmeter. To measure bubble displacement, a bridge circuit detects the difference in capacitance between the two sensing electrodes and the reference electrode. Using this circuit, a tiltmeter level vial with 2 mm deflection for 5 arc-seconds of...
Transistor Ql, a 2N3563, and its associated components form an oscillator circuit that will oscillate if, and only if, a good crystal is connected to the test clips. The output from the oscillator is then rectified by the two 1N4148 diodes and filtered by CI, a,01 Âµ capacitor. The positive voltage developed across the capacitor is applied to...
Care must be taken to eliminate any stray currents from flowing into the current summing node. This can be accomplished by forcing all points surrounding the input to the same potential as the input. In this case the potential of the input is at virtual ground, or OV. Therefore, the case of the device is grounded to intercept any stray leakage...
Measuring phase difference
This method is capable of measuring phase between 0 to Â±180Â°. The generated square waves A and are fed to a D flip-flop which gives an output C equal to logic 1 when input 1 leads input 2 and equal to logic 0 in case of lagging. When C = logic 0, the output of the amplifier F will be positive proportional to the average value of the output...
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...
Multimeter AC voltage measuring circuit
Measuring the voltage converter can be set to switch to the right, left AC voltage range selector switch to any one file, then
Voltage output humidity sensor meter circuit HM1500 / 1520 with microprocessor PIC16F874
Intelligent humidity meter circuit by the HM1500 / 1520 humidity sensor and MCU configuration shown in Fig. The meter + 5V power supply, with four common cathode LED digital tube. CCP
Frequency Meter Circuits
VU Meter Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
DIY HV Variable Capacitor
DIY PMA Alternator Plans
Digital Signal Integrity