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8051 / 8052
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4 Band Resistor
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Logic probe yields three discrete states
The circuit uses a dual LED. When power is applied to the probe throughthe power leads, and the input is touched to a low level or ground, Ql is cut off. This will cause Q2 to conduct since the base is positive with respect to the emitter. With Ql cut off and Q2 conducting, the green diode of the dual LED will be forward biased, yielding a green...
The injector is a CMOS oscillator with period approximately equal to 1 x Cl x R2 seconds. The values are given for 1 kHz operation. Resistors R3 and R4 divide theoutput to 1 V; Whereas the oscillator employs the gates in their digital mode, the tracer used them in a linear fashion by applying negative feedback from output to input. They are used...
The unit has a separate amplifier and oscillator section allowing them to be used separately if need be. The injector is a multivibrator running at 1 kHz, with R5 andR6 dividing down the output to a suitable level (Â«1V). The tracer is a single-stage amplifier that drives the high impedance earpiece
Cmos logic probe
The logic probe can indicate four input states, as follows: floating inputâ€”all LEDs off
100K megohm DC probe
A 741 op amp is used with 100% ac and dc feedback to provide a typical input impedance of 1011 ohm and unity gain. To avoid hum and rf pickup the input leads should be kept as short as possible and the circuit should be mounted in a small grounded case. Output leads may be long since the output impedance of the circuit is a fraction of an ohm
Transistors Q1 and Q2 form a buffer, providing the probe with a reasonable input impedance. Q3 and Q4 form a level detecting circuit. As the voltage across the base-emitter junction of the Q3 rises above 0,6 V the transistor turns on thus turning on Q4 and lighting the red (high) LED. Q5 and Q6 perform the same function but for the green (low)...
Logic test probe with memory
There are two switches: a memory disable switch and a pulse polarity switch. Memory disable is a push-button that resets the memory to the low state when depressed. Pulse polarity is a toggle switch that selects whether the probe responds to a high-level or pulse (+5 V) or a low-level or pulse (ground)
The probe indicates a high or low at 70% and 30% of V+ (5 to 12 V). One section of the voltage comparator (LM393) senses V in over 70% of supply and the second section senses V in under 30%. These two sections direct-drive the appropriate LEDs. The pulse detector is a CMOS oneshot (MC14538) triggered on the rising edge of the LM393 outputs...
Audio-rf signal tracer probe
This economical signal tracer is useful for servicing and alignment work in receivers and low power transmitters. When switched to RF, the modulation on any signal is detected by the diode and amplified by the FET
Ttl logic tester
Gates Gl and G2 together with resistors Rl and R2 form a simple voltage monitor that has a trip point of 1 volts. Gate G3 is simply an inverter. The display section of the tester consists of a common anode alphanumeric LED and current-limiting resistors
The low Rds and high peak current capability ofthe DG419 makes it ideal for discharging anÂ·integrator capacitor. A high logic input pulse disconnects the integrator from the analog input and discharges the capacitor.
When a large number of channels are multiplexed, the outputs of two or more multiplexers can be connected together and each multiplexer sequentially enabled. In the inhibit mode. the multiplexer draws less power and its output and inputs act as open circuits. Theoretically, an infinite number of channels can be accommodated in this way; in...
This circuit reconstructs and separates analog signals which have been time-division multiplexed. The conventional method, shown on the left, has several restrictions, particularly when a short dwell time and a long, accurate hold time is required. The capacitors must charge from a low-impedance source through the resistance and...
This circuit shows a typical multiplex system intended to carry one of 8 inputs into a remote location. A 5-V pulse train is sent down a separate channel to perform timing and synchronizing functions. A 15-V reset pulse is superimposed on the 5-V clock, which is detected by the MM74COO in the receiver.
The probe relies on the power supply of the CUT (circuit-under-test). The input to the probe, at probe tip, is fed along two paths. One path flows to the clock inputs of U2a and U2b. The other path feeds both the inverting input of Ulc, which is set up as an inverting-mode integrator, and the noninverting input of Ulb, which is configured as...
The pulser generates pulses at a user-selected frequency of 0.5 or 500 Hz, with a pulse width of about 5 ms. If the input to be pulsed is already being driven high or low by another output, the pulser automatically pulses the input to the opposite logic state.
Digital Levels Scope Displays 2 Logic Signals On 1 Scope
Using this simple resistor circuit, you can trick your oscilloscope into displayin
The HA-4900 series comparators can be used as versatile logic interface devices, as shown in these circuits. Negati
Fast Binary Adding Circuits
Some circuits that add binary numbers have problems with time delay caused by carry propagation. This has been
Universal Test Probe
The compact test probe provides rapid "measurement" of voltage levels at digital gates, fuses, diodes, batteries, and
S1Ngle-Ic Logic Probe
This logic probe uses a CD4009 CMOS hex inverter. The characteristic high-input impedance of CMOS gives the advantage
Â· This circuit is used for analog signal selection or time division multiplexing. As shown, the feedback signal places the selected amplifier channel in a voltage follower (noninverting unity gain) configuration, and provides very high input impedance and low output impedance. The single package replaces four input buffer amplifiers, four...
Multi-Tester Logic Probe Signal Tracer And Injector
This circuit for a test set contains a signal injector (U1A/U1B) and associated com
555 tri-state acousto-optical logic circuit
As illustrated, 555 and R4, R5, C1 and so connected as a controllable multivibrator mode, which force reset terminal 4 feet to explore pen, control terminal 5-pin external level high and low logic level input related.
Door light emitting logic circuit with CD4069
Logic pen also known as logic detection probe, it is a common tool in the digital circuit detection logic state of each point. Digital circuit logic state is generally divided into three types: namely, a high level "l", the low level "0"
LED display driver circuit a
As shown in Figure is a large high-brightness LED driver circuit for a sufficient drive current, integrated circuits using a 7447A or 74247. Digital display tube has eight ligh
LED display control circuit diagram of a counter
As shown, in FIG a decimal seven storage - Decoding - drive unit 74 143, this unit has a constant output for all segments. Each at a voltage of 5V when the current is about 15
High Speed Logic Astable Multivibrator (MC74HC04)
The MC74HC04 IC is a low cost CMOS Hex Inverter. I used this type mainly because, it is what I have, although you can use LS type but, with a little modification or exemptions..
16-bit adjustable reference uses 8-bit digital potentiometers
It may be easy to find a precision voltage reference for your application; however, a programmable precision reference is another matter. The circuit in Figure 1 yields a precision reference with an LSB of 62.5 µV. The circuit is a 16-bit DAC using three 8-bit digital potentiometers and three CMOS op amps. Each digital potentiometer operates as...
5V logic pulser is battery-powered
A battery-powered, pushbutton-triggered TTL/CMOS-compatible source of debounced 5V logic pulses is a simple but handy piece of test equipment to have in any tool kit (Figure 1). The circuit`s battery-powered operation complicates what would otherwise be a trivial exercise in switch-bounce and timing-circuit design. The convenient use of battery...
Build a PIC controlled DDS VFO, 0 to 6 MHz
Almost any 2x16 character LCD module with Hitachi HD44780 controller chip will work. The LCD pin numbers on the schematic are not valid for all LCD modules. Please check the actual signal names on your particular LCD module. The selected DFCW frequency offset will be added to the output frequency when the DFCW input is grounded. This input has a...
The 6090 Digital Decoder
This is an image Schematic. No Description available.
Digital to Analog Circuits
Analog to Digital Circuits
Data Logging Circuits
Data Bus 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...
Digital Signal Integrity
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