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
The circuit can be used to simulate large capacitances using small value components. With the values shown and C - 10 ÂµÂ¥, an effective capacitance of 10,000 ÂµF was obtained. The Q available is limited by the effective series resistance.
Simple continuity checker
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.
The shift pulse amplitude is less than 15 volts. If a stage is off, the shift pulse will not be coupled to the next stage. If it is on, the diode will conduct triggering the next stage. Just prior to the shift pulse the anode supply is interrupted to turn off all stages.
Car Exhaust Meter
Bridge circuit contains two resistors lOO-ohm (R3 and R4), and two thermistors (Tl and T2). At room temperature, the resistance of T1 and 1'2 is about 2000 ohms. When they are each heated to 150 Â° C by an RNA 10 current, the resistance value decreases to 100 ohms. So. the four elements include a bridge circuit. CO is a characteristic that...
Static charge-electricity detector
The detector will sense static charges and free ions in the air. It can be used to indicate the presence of ion emission, high voltage, static electricity, and electrostatic fields. The ground can be an earth ground or a touching metal by your hand.
Battery status indicator circuit diagram
741 op amp can be used as a voltage comparator. Non-inverting input and a zener control source. The reference voltage is 5.1V. R2 can adjust the in-phase input voltage becomes
The power indicator circuit
ACER PM02 MP4 machine shows voltage status indicator circuit, when there is power red LED lights when entering the work, the green LED lights.
Used in conjunction with multimeters FET Vp Vas checker
Chen is in the OP put too amplifying circuit, so that the comb over current feedback loop with input resistance determined current roll, so FET drain current, a gate by the det
Clamp-on-current probe compensator
A clamp-on "current probe" such as the Tektronix P6021 is a useful means of displaying current waveforms on an oscilloscope. Unfortunately, the low-frequency response is somewhat limited, as shown in the Table. The more sensitive range on the P6021 is 2 mA/mV, but it has a roll-off of 6 dB per octave below 450 Hz. The compensator counteracts the...
Build your own bypass-capacitor tester
The circuit in Figure 1 tests these characteristics. It charges the capacitor under test through 100 k for approximately 1 msec and then discharges it through 10 for approximately 40 nsec. The cycle then repeats. The circuit uses a double-sided copper-clad pc board. All the components except the 10 resistor connect to one side of the board, so...
Schottky Field Strength Meter
When an antenna is attached, (or even if not, in the presence of a strong RF field) the field strength meter has a moving coil meter to indicate relative field strength. The box holds a Schottky diode detector, a DC amplifier, and a meter display. If the parts used in construction are the same values shown in the schematic, the meter shows full...
Clock multiplier circumvents PLL
Using a standard PLL circuit, such as the CMOS 4046B with some passive components, is a well-known way to design a clock multiplier. Unfortunately, using a PLL in a digital circuit has two disadvantages: It takes a long time for the circuit to reach a stable output frequency, and the frequency-drift compensation has a complex design.
Simple Transistor Tester
This is basically a high gain amplifier with feedback that causes the LED to flash at a rate determined by the 10u and 330k resistor. Remove one of the transistors and insert the unknown transistor. When it is NPN with the pins as shown in the photo, the LED will flash. To turn the unit off, remove one of the transistors.
LED Crystal Tester
Transistor Q1, 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 1N4148 signal diode and filtered by C3, a 100pF capacitor. The positive voltage developed across the capacitor is applied to...
Inductance adapter for frequency meter
The following circuit enables me to measure inductance of the inductor labeled LX which is the inductance to be measured. The o/p of the circuit is a TTL square wave whose frequency relates to the inductance being measured. The heart of the circuit is the buffer colpitts oscillator(the first stage) which resonates with the unknown inductance to...
An RF probe is used to directly measure the level of RF voltage present at a particular point and is one of the most useful test instrument in the hands of the home brewer. It is normally used with a digital multi meter to indicate the voltage level as dc voltage which is equivalent to the RMS value of the RF voltage being measured. However, the...
Scope Probe Adapter
The capacitance between the wire and the probe would form a capacitive voltage divider with the probe's input capacitance, and at frequencies significantly higher than the low frequency roll off created by the probe's input capacitance and the probe's resistance, the wave form would be faithfully reproduced, although it would have a reduced...
MOSFET Tester circuit
This is a variation on the astable multivibrator. Circuit was recently developed to test for N-mosfets(the power kind e.g irf830). I don?t claim circuit can test all bad mosfets or all fault mosfet conditions. If mosfet is working it will operate in the astable multivibrator circuit causing the Led to flash. A bad mosfet will not cause the LED...
Simple Digital Potentiometer with DS1869
The experimenter's pot is a solid state potentiometer using Dallas semiconductor?s DS1869 and National?s LM78L05 two electrolytic capacitor two small push button switch and two optional Molex connector. this project is very useful especially in finding the right value of resistor in your experiments, you can attach this circuit to your next...
Oscilloscope AC Probe
The probe described here was designed to be used over the range of several tens of Hz to a couple MHz with currents from a few tens of milliamps to about 10 amps peak-to-peak. Formulae are give which will allow you to create a design suitable for your own applications. To use this probe, a wire is connected in series with the load that you want...
µCurrent Adaptor for multimeters
The µCurrent is in many cases also able to improve upon your meters current range accuracy by using your meters more accurate mVDC or mVAC voltage ranges instead to display the DC or AC current. With AC the frequency response extends flat up to 10KHz, but THD increases substantially above 2KHz. Still a very respectable AC response range,...
1 Khz Inductance Meter ATTINY861
1 kHz is a commonly used test frequency, and I resolved to see if I could make an inductance meter that uses a 1 kHz test signal at a low level. I also wanted to use a low level test signal so that the test current would have a minimal effect on the measurement. Magnetic cores, and soft ferrites in particular, change in permeability as a...
16-300 MHz Testing Colpitts oscillator
The circuit is a modified Colpitts oscillator, tuned with MV209 varactor diodes. The resonating inductor and the drain choke are selected by a rotary switch. 1N5711 Schottky diode, D, clamps the maximum positive voltage on the gate of oscillator FET, Q1 to just above ground to reduce the distortion in the wave form on the gate of Q1. Buffer Q2...
Negative Resistance Oscillator with Tunnel Diode
This circuit can be easily powered from a 1.5 volt battery. One characteristic of N type negative resistance devices is that they typically require a very low bias source resistance in order to keep the bias voltage stable within the negative resistance region. With too high of bias resistance, the voltage, as it enters the negative resistance...
220V Mains Quality Monitor
With this circuit you will be able to monitor the quality of the mains. There are 4 distinct sections, each supervising a parameter pertinent to the quality of the supply line. The noise section consists of a 50Hz filter and a speaker where you will hear the noise present on the line. The bicolor LED should be adjusted for the least light with...
Analogue Tachometer and Dwellmeter
This circuit as first published in Wireless World September 1975 and subsequently in MECRM. It's built around a TTL quad NOR gate, though CMOS could be used.
Km Counter / meter circuit
This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants' pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km. and its dot is always on to separate Km. from hm. The rightmost display D1 (the least significant digit)...
Finding an Electrical Short
Over time, many things can cause electrical problems with your Mustang. Components will get old and worn or a wire can rub against something and expose the wire to metal. I have seen where a body shop will inadvertently crimp a wire when they install a body panel. Sometimes, when mechanical repair is done, the wiring just gets in their way. This i
12V Battery Checker Circuit
This is a 12V battery checker circuit that uses 3 LEDs that light up at their respective voltages. The red LED lights up when the battery voltage is between 8 to 10V, the orange one at voltages between 10. 5V to 12V and the green one when the battery voltage is above 12. 5V. This is a tried and tested battery checker circuit using one NPN and...
IR Remote-Control Checker
R2_47R 1/4W Resistor D1_LED (Any dimension, shape and color) Q1_Infra-red Photo Transistor (Any cheap type) Q2_BC327 45V 800mA PNP Transistor SW1_SPST Toggle or Slide Switch (Optional, see Note) B1_3V Battery (2 x 1. 5V AA, AAA or smaller type Cells in series) A very simple device allowing a quick check of common Infra-red Remote-Controls can be us
ADC Tester (A2100)
The ADC Tester (A2100) is a LWDAQ device that records the output and power consumption of two ADC s. Its original purpose was comparative testing of two ADCs at different temperatures, but it turned out that the A2100 makes a good dual-channel eighteen-bit oscilloscope. Figure: ADC Tester (A2100A) with Two LTC1865L Auxilliary Boards. The flex cabl
BC107 Transistor For 12V Battery Operated Heater Circuit
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