Display Circuit

A device designed for measuring time and temperature used in chemistry laboratory. The circuit employs a 89C4051, 20-pin CMOS Microcontroller with built-in 4kB code memory. Temperature was measured by LM35D, National Semiconductor Temperature sensor producing 10mV/°C. The CA3162, 3-digit DVM converts dc output provided by LM35D and sends BCD output to port1 (P1.0-P1.3). The program resided in code memory of 89C4051 was written in ‘C’ language, thermo.c. The program read BCD output from the A/D converter, performs digital filtering,10-point moving average, and sends the output reading to a 16x1 line LCD display. A 10ms cputick was used as a timebase producing 1 s for time counting. The LCD displays time in 1 s and temperature in 0.1°C resolutions...

Hi-Low Logic Digital tester

Hi-Low Logic Digital tester

This tester, the logic level digital signals indicate on a 7-segment display. The display shows an H as the input signal is high. When the signal is low, the display shows an L on. If the input is open, the display shows N. The circuit consists of a TTL NAND IC type 74LS00 and three transistors. The NAND gates ensure that the right segments of the display can be controlled. ..

Digital counter circuit

Digital counter circuit

With this counter you can count laps for example (in conjunction with the Simple light trap ). The circuit uses two TTL ICs 74LSxx the series. The left IC is a decimaalteller. The input pulses 14 are counted and converted to the corresponding BCD code. This code is passed to the second IC, which is a code converter and display driver. Here the BCD code correct the display driver for LD1. ..

99 mV to 999 mV meter schematic

99 mV to 999 mV meter schematic

This circuit can for example be incorporated into a diet to pressure warning. The meter can measure voltages from -99 mV to 999 mV. The circuit uses two ICs, the CA 3161 and CA 3162. IC1 converts the analog signal into a digital signal. IC1 is also the multiplexed signal to T1-T3 can be controlled. The BCD code is then fed to IC1 IC2, a BCD/7-segments converter. Then the signal is fed to the displays. Pin 6 of IC1 (hold) can be used for a number of things. When pin 6 is grounded or open, the 4 Hz sampling frequency. When pin 6 is at 1.2 V, then enter the HOLD function is activated. ..

Digital Clock Timer schematic

Digital Clock Timer schematic

This clock timer uses a PIC16F628 microcontroller to display 3 and 1/2 digit time and control an external load. The clock includes a calendar with leap year and optional daylight savings adjustments. The timer output can be set from 1 to 59 minutes and manually switched on and off. The clock also has a correction feature that allows an additional second to be added every so many hours to compensate for a slightly slow running oscillator. The oscillator uses a common 32.768 KHz watch crystal and the frequency can be adjusted slightly with the 24pF capacitor on the right side of the crystal...

Digital Countdown schematic with 555

Digital Countdown schematic with 555

This circuit provides a visual 9 second delay using a 7 segment digital readout LED. When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high. When the switch is opened, the timer produces an approximate 1 second clock signal, decrementing the counter until the 0 count is reached. When the zero count is reached, the 'carry out' signal at pin 7 of the counter moves low, energizing the 12 volt relay and stopping the clock with a low signal on the reset line (pin 4). The relay will remain energized until the switch is again closed, resetting the counter to 9. The 1 second clock signal from the 555 timer can be adjusted slightly longer or shorter by increasing or decreasing the resistor value at pin 3 of the timer. ..

Digital Clock with Solar Regulator

Digital Clock with Solar Regulator

The basic clock circuit (top schematic below) is similar to the binary clock (on another page) and uses 7 ICs to produce the 20 digital bits for 12 hour time, plus AM and PM. A standard watch crystal oscillator (32,768) is used as the time base and is divided down to 1/2 half second by the 4020 binary counter. One half of a 4013 data latch is used to divide the 1/2 second signal by 2 and produce a one second pulse that drives the seconds counter (74HC390 colored purple). The minutes are advanced by decoding 60 seconds (40 + 20) and then resetting the seconds counter to 0 and at the same time advancing the minutes counter. The same procedure is used to advance the hours. The second half of the 4013 latch is used to indicate AM or PM and is toggled by decoding 13 hours and resetting the hours to 0 and then advancing the hours to "one"...

Battery capacity / Accumulator Charge Meter

Battery capacity / Accumulator Charge Meter

The instrument used to measure battery capacity. The battery may be charged to any current in the range 0-3 A. The load current may be constant, may change over time or even break off completely. Unloading stops when the battery voltage drops below the set limit. Measuring the battery at various discharge currents, we consider the purpose for which it can still be used. Meter is based on the current-frequency converter. The output pulses of the converter are counted in counter, whose contents are displayed on the screen. The appropriate choice of transfer constants are displayed directly passed through the hub size. For example, a current of 1 A for 1 hour with loads of pulses 1000. However, if diminishing current to 100 mA, the output frequency is 10 times lower transmitter and pulses will be only one hundredth To read in Pulse 1000, the same as in the previous case, the converter would have to pass through stream 10 times longer. For practical reasons, however, given the current transmitter frequency several orders of magnitude higher and the required number of pulses per unit time decreases divider. We do not have to monitor battery voltage, the meter is completed circuit, which disconnects the load is reduced when the voltage is below the set limit. Involvement of the current-frequency converter is in Figure 1 The converter circuit using MAX471, which is designed to monitor the battery charge in portable devices. Monitored current passes between the pin RS + and.....

Digital Volt and Amp Meter

Digital Volt and Amp Meter

The PIC Microchip Processor must be programmed before it will function as a Volt & Amp meter. There are many internet sites and PIC programmers that you can use. I used a Microchip MPLAB ICD 2 during the project. You might need to made changes to the circuit to accommodate a different type of programmer, do read the programmers instructions carefully. The circuit relies on the internal analogue to digital converter (ADC) of the PIC Microchip Processor. The accuracy is dependant on scaling the input voltage for the ADC for all three measurements. The good news is that both the PIC's which can be used for this project have 10-Bit resolution ADC units which should work adequately in most circumstances...

Km Counter / meter circuit

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) shows hundreds meters and its dot lights after every 50 meters of walking. A beeper (excludable), signals each count unit, which occurs every two steps. A normal step is calculated to span approx. 78 centimeters, thus the LED signaling 50 meters lights after 64 steps or 32 mercury switch's operations, the display indicates 100 meters after 128 steps and so on. For low battery consumption the display lights only on request, pushing P2...

Digital Voltmeter with ICL7129ACPL A/D converter

Digital Voltmeter with ICL7129ACPL A/D converter

This 4 1/2-digit DVM circuit is built around a Maxim ICL7129ACPL A/D converter and LCD driver. An ICL8069 CCZR 1.2-V band-gap reference diode is used for a voltage reference. S2a-b-c select one of four ranges up to 200 V (maximum). The meter also has a piezoelectric buzzer for continuity testing. S3 selects either DVM or continuity. Crystal 1 can be changed to 100 kHz if maximum rejection of 50 Hz is desired. The crystal normally provides 120 kHz for best 60-Hz rejection. This is caused by the dual-slope conversion technique used in IC1...

Telephone DTMF decoder Display

Telephone DTMF decoder Display

The given circuit, when connected in parallel to a telephone, dis- plays the number dialled from the telephone set using the DTMF mode. This circuit can also show the number dialled from the phone of the called party. This is particularly helpful for receiving any number over the phone lines. The DTMF signal generated by the phone on dialling a number is decoded by DTMF decoder CM8870P1 (IC1), which converts the received DTMF signal into its equivalent BCD number that corresponds to the dialled number. This binary number is stored sequentially in 10 latches each time a number is dialled from the phone. The first number is stored in IC5A (1/2 of CD4508) while the second number is stored in IC5B and so on...

Quiz game schematic

Quiz game schematic

This jam circuit can be used in quiz contests wherein any par- ticipant who presses his button (switch) before the other contestants, gets the first chance to answer a question. The circuit given here permits up to eight contestants with each one allotted a distinct number (1 to 8). The display will show the number of the contestant pressing his button before the others. Simultaneously, a buzzer will also sound. Both, the display as well as the buzzer have to be reset manually using a common reset switch. Initially, when reset switch S9 is momentarily pressed and released, all outputs of 74LS373 (IC1) transparent latch go high since all the input data lines are returned to Vcc via resistors R1 through R8...

Scoring Game circuit

Scoring Game circuit

You can play this game alone or with your friends. The circuit comprises a timer IC, two decade counters and a display driver along with a 7-segment display. The game is simple. As stated above, it is a scoring game and the competitor who scores 100 points rapidly (in short steps) is the winner. For scoring, one has the option of pressing either switch S2 or S3. Switch S2, when pressed, makes the counter count in the forward direction, while switch S3 helps to count downwards. Before starting a fresh game, and for that matter even a fresh move, you must press switch S1 to reset the circuit. Thereafter, press any of the two switches, i.e. S2 or S3. On pressing switch S2 or S3, the counters BCD outputs change very rapidly and when you release the switch, the last number remains latched at the output of IC2...

5x7 LED display schematic

5x7 LED display schematic

Your 5x7 display is my favourite toy; the tunes and graphics in the elevator display always impress my mates! Since building the display I developed my own 400 dot matrix using a pic and the SN74154 [4bit binary to 1 of 16 demultiplexer\counter] - in place of the 4017. It works well but I still have to hook it up to my computer to change the scrolling message. When I get time I will write another program that will make it easier to program the message board via an I.R. remote...

Sort List by: Alphabetic Date Clicks Rank ascending | descending

Neighbour Categories

Readout Circuit	Digital to Analog	Data Logging	Decoder Circuit
Logic Circuit	Analog to Digital	Data Bus Circuit