Readout Circuits

This is the fully featured, jammed packed temperature readout unit. I can measure temperature from up at 8 DS1820 digital temperature sensors all on the same 1-wire bus. That's right only 3 wires are needed to go to all the temperature sensors, GND, VCC and 1-wire data. All sensors will connect to the same cable! Anyone who has used the DS1820's will know that each DS1820 sensor will have a 48bit serial number that is used to address the sensors. With this unit the.....

This circuit is a small digital ?roulette''. It is constituted by oscillator IC1, the counter IC2, the transistors Q1-7 that drive the display common cathode DSP1. The supply basically becomes from a battery 9V, but can become also from one power supply. The regulation of frequency should become in the 10HZ or little bigger, with to pontesometer TR1 combination with the C1, which we can change the capacity, changing thus and the frequency of oscillator. Bigger frequency.....

The circuit uses a serial-in-parallel out shift register, 74HC595 for receiving serial data from uController board. See example of U5 in the schematic, SER is for data input, SRCLK is shift clock and RCLK is Latch clock. Each data bit is shifted into the register on rising edge of the shift clock. When all data bits are shifted into the 8-bit register, the rising edge of RCLK will clock the data to be latched at each output bit, i.e. QA - QH...

The timer is proposed an effective model for controlling an external load 8A/380V. Equipped with a 68HC11 mu.P associated with an 8 MHz crystal, it can get very precise programmable durations. Two lines are planned: from 0 to 99 seconds and from 0 to 99 minutes. Both displays allow programming in conjunction with a 4-button keypad. They also display the count of elapsed time. The relay output double contact work controls the external load...

This is one of the most accurate and simplest LC inductance / capacitance Meters that one can find, yet one that you can easily build yourself. This LC Meter allows to measure incredibly small inductances starting from 10nH to 1000nH, 1uH to 1000uH, 1mH to 100mH and capacitance from 0.1pF up to 900nF. LC Meter`s circuit uses an auto ranging system so that way you do not need to spend time selecting ranges manually. Another neat function is the "Zero Out" switch that will.....

A project that includes a stage with three selectable gains (0.1, 1.0, and 10) requires that the rotary-gain switch also function to illuminate one of three LEDs. These panel-mounted LEDs serve to indicate the gain in use. This arrangement requires two switch sectionsone for selecting the op amps gain-set resistor and one to light the corresponding indicator LED. The circuit in Figure 1 requires only one more switch section to provide a true, two-digit, seven-section.....

Using only 2 capacitors, 3 resistors, 4 seven-segment Display, 1 xtal, 2 switches n.o. and 1 Microcontroller PIC, you can build this Digital Led Clock. you can use common anode or common cathode display, just select the display type. Here is the pinout information: Pin 3 defines the display type. If you will use common cathode display, connect to negative. For common anode, connect to positive. Here is a example circuit:..

The digital clock of circuit, has as base one IC, the MM5314N, in which are contained all the circuits that need. The IC1 collaborates with six Display of common anode, that are not critically as materials. You can select what dimension, you want it is enough you adapt pins their in the circuit. The display are drive by a system of polyplexis and are drive by thirteen transistors. For timing the circuit, is used the frequency of network (50HZ). This solution is the.....

The circuit in Figure 1 uses a PIC16C55 µP to read 10-bit binary data and directly display the data in decimal format on three common-cathode LED displays. If value of the data exceeds 999, the displays show three hyphens (---) to represent overflow. The PIC16C55 has high drive capability. Each output pin can source 20 mA and sink 25 mA; the outputs can thus directly drive the LED display...

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.....

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......

The analog to digital converter (ADC) is a commonly required in most of the projects. Analog voltage measurement can be done using the ADC hardware built in together in a PIC. The picture below show a simple setup for measuring the voltage through the adjustment of the potentiometer. PIC used in this example come with a 10 bit ADC. In the picture the hex value shown is the ADC value acquired from the hardware. After a simple conversion the voltage can be obtain from this.....

The use of pulse width modulation (PWM) is common for the use of controlling power to a particular electrical device. Motor speed control, LED contrast control, power supplies are some of the example usage of PWM. 18 series PIC always come with a CCP module which is capable of generating PWM. The picture below shows an example of using the capture/compare/pwm (CCP) module to control the LED brightness. PWM duty cycle is set accordingly using the value obtain from the.....

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.....

This sign I designed uses no microprocessor. It has an eprom and multiple counters. As in most electric signs, the LEDs are matrixed, and strobed very quickly to make it possible for all 70 LEDs to appear lit. This sign is strobed horizontally, unlike most large signs which are strobed vertically. I did it this way because electrically it was simpler. The eprom has 8 outputs, of which I used 7 of them to drive the 7 horizontal rows. The eprom outputs are not strong, so.....

This project is a PLL synthesized FM radio which can decode DTMF. The receiving frequency can be set by the PLL circuit from 80-140MHz. The receiver is VERY stable, high sensitivity and easy to build and tune. The FM receiver can decode DTFM signals from a transmitter and present the DTMF data on three LED display. The complete background about this project can be found at my "Wife replace" project. This part is a FM receiver based on a PLL synthesizer UMA1015. The.....

The Car Temperature Gauge is basically the same circuit as March's project with some minor changes to the input circuit. This circuit will display the water temperature to 1 degree resolution...

This Circuit uses a CD40110BE, Up/Down Counter IC's. This IC is able to Source Each Segment with 25 mA, Giving a Very Nice Bright Display. The 7 Segment Displays MUST be a Common Cathode Type, as I have used here. All the UnMarked Resistors should be at least 680 Ohms for Up To 12 Volts Supply Voltage. For Higher Supply Voltages up to 18 volts or Reduced Currents, I would suggest Increasing these Values to 1500 Ohms. Or if you want "Reduced Power" and "Brightness", Adjust.....

This very simple counter can be used to measure the frequency of various wireless devices. Applies in reviving the transmitter and its operation as a control monitor frequency. It can be used as a scale to the receiver. Due to the simplicity of the counter should not miss any of the equipment bastlí?e that similar facilities are still owned. Buying the parts is not a significant financial burden and required the program to the PIC is available for download. To measure the.....

This is the first interfacing example for the Parallel Port. We will start with something simple. This example doesn`t use the Bi-directional feature found on newer ports, thus it should work with most, if no all Parallel Ports. It however doesn`t show the use of the Status Port as an input. So what are we interfacing? A 16 Character x 2 Line LCD Module to the Parallel Port. These LCD Modules are very common these days, and are quite simple to work with, as all the logic.....