Rongge

Now a day, everyone wants to control their appliance wirelessly (i.e. remote control). Here is a simple tested and inexpensive remote control switch utilizing reading available components.   Circuit Description of infrared (IR) remote control switch As in all wireless systems Infrared (IR) remote control switch also comprise two major section i.e. transmitter and receiver section. Transmitter Section: – The logic of this section is simple and is build around most versatile IC NE555 (IC 1 ), configured as astable multivibrator to produce frequency about 38 KHz. This is so, because IR module receiver used here works in range of 38 KHz frequency. Timing component of infrared remote control switch is resistor R 1 and R 2 and capacitor C 2 , determine the range of oscillating. Where, formula of generated frequency (F) from transmitter section IR remote is given by F = 1.443 / (R 1 + 2R 2 ) C2 The output frequency from pin 3 of IC 1 is fed to base of transistor T 1 through resistor ...

Here is a simple oscillator circuit that varies the duty cycle over a wide range without affecting the frequency. It is a variation of the simple 555 astable oscillator. Initially, I told a reader that there was no standard 555 circuit that could do this, but then the grey matter started working. The use of an air-variable capacitor for frequency control is a mind-blower—nothing short of a time warp! 555 Duty Cycle Control Schematic Overview When potentiometer R1 is centered, operation is obvious and the duty cycle is 50%. However, as R1 is rotated in either direction the charge time and discharge times vary accordingly. The two sides of R1 have independent steering diodes (D1 & D2). C1 & C2 make up the timing capacitor. Pins 2 & 6 of the 555 are the upper and lower thresholds of the input comparators. The charge /discharge voltage is taken from pin 3 because it has rail-to-rail voltage swing, and the open collector output (pin 7) cannot do this. The rectangular waveform o...

For those interested in reproducing this example: The board is called “EP2C5 Mini Board” and has a EP2C5T144C8 Cyclone II FPGA on it I used a standard, 9grams micro RC Servo. I used a 28BYJ-48 stepper motor and it’s driver (you can purchase these as a bundle for very cheap on dealextreme or banggood) I used the free edition of Quartus II from Altera, version 13.0 SP 1 (be careful, later versions do not support Cyclone II FPGAs anymore) I created a simple project, pasted all this code as a single module (it would of course be cleaner to separate the RC Servo and stepper control code into independent modules) made the “Top level entity” in the General configuration page equal to “counter” (the name of my module) used the Pin Planner to assign the inputs/outputs as follows: [ ]

PT2350 is a tone control subwoofer cross-over low pass filter chip utilizing CMOS Technology. It features a tone control range of + 10dB (50Hz, 4 KHz) and subwoofer low pass filter of the second order Sallen Key Design. The roll-off point can be adjusted by changing the value of the external capacitor. Pin assignments and application circuits are optimized for easy PCB Layout and cost saving advantages. CMOS Technology 2-Channel Input 3-Channel Output (Including 1 stereo Output and Subwoofer Output) Low Total Harmonic Distortion (THD<0.01%, Subwoofer THD<0.2%) High S/N Ratio (S/N Ratio <-87dB, A-weighting) Least External Components Adjustment of Frequency response by changing the value of the external component Single Power Supply: 3 to 8.5 Volts Available in 20 pins, DIP or SO Package PARTS Resistors 2------ R1,R2-------------- --------- 10k / 1% / metal film Capacitors 2------ C9,C10------------- -------- 4.7nF / 63V / polyester / raster R. 5mm 3------ C1,C7,C8-------- -----...

This Precision Amplifier With Digital Control circuit diagram is similar to the preceding circuit of the attenuator. Gain of up to 100 can be achieved in this configuration, which is useful for signal conditioning of low output of transducers in millivolt range. The gain selection resistors R3 to R6 can be selected by the user and can be anywhere from 1 kilo-ohm to 1 meg-ohm. Trimpots can be used for obtaining any value of gain required by the user. The resistor values shown in the circuit are for decade gains suitable for an autoranging DPM. Resistor R1 and capacitor C1 reduce ripple in the input and also snub transients. Zeners Z1 and Z2 limit the input to ±4.7V, while the input current is limited by resistor R1. Capacitors C2 and C3 are the power supply decoupling capacitors. . Precision Amplifier With Digital Control Circuit Diagram Precision Amplifier With Digital Control Circuit Diagram Op-amp IC1 is used to increase the input impedance so that very low inputs are not loaded on ...

My first DoorBell Mote prototype was working nicely and it allowed monitoring the door bell (while also triggering it remotely – toddlers love it). But I wanted more. On weekends the family likes to get a well deserved nap during the day and often those pesky solicitors ring the bell and wake everyone up. So naturally the doorbell has to be disabled also, without major effort or any disconnected wires. Sounds like the perfect addition to the Door Bell Mote. So I made a new revision and a proper PCB for this, below is the schematic with the changes and the proto PCB from OSHPark. Actually I made more changes to the schematic after putting together the PCB, so there are some differences. I’ve tried a LTV814H optocoupler for AC detection instead of the more expensive H11AA11, it works just as well, but both can be used on this PCB. [ ]

Monitoring of an inverter during operation has being the major challenge faced by local inverter Manufacture which has lead to low demand for locally built Inverters due to sudden break down or Battery being overcharged. most of the Inverter schematic claimed or used by Local Inverter Manufacture downloaded from the internet are for tutorial purpose not not for commercial there are tendencies for failure therefore it is time for us to start developing things of our own... proudly NIGERIA...... The featuring M.C.U is the Microchip PIC16F876A FEATURES OF THE ABOVE SCHEMATIC ARE STATED BELOW : INVERTER PROTECTION : LOW-BATTERY SHUTDOWN                                              : OVER LOAD SHUTDOWN INPUT                                              : O/P SHORT CCT SHUT-DOWN INPUT                                              : HIGH TEMPERATURE SHUT-DOWN INPUT                                              : LOW-BATTERY : BEEP START AT 11 V                                              :INVE...

This circuit confuses the infra-red receiver in a TV. It produces a constant signal that interferes with the signal from a remote control and prevents the TV detecting a channel-change or any other command. This allows you to watch your own program without anyone changing the channel !!    The circuit is adjusted to produce a 38kHz signal. The IR diode is called an Infra-red transmitting Diode or IR emitter diode to distinguish it from a receiving diode, called an IR receiver or IR receiving diode. (A Photo diode is a receiving diode). TV Remote Control Jammer Circuit diagram : There are so many IR emitters that we cannot put a generic number on the circuit to represent the type of diode. Some types include: CY85G, LD271, CQY37N (45¢), INF3850, INF3880, INF3940 (30¢). The current through the IR LED is limited to 100mA by the inclusion of the two 1N4148 diodes, as these form a constant-current arrangement when combined with the transistor and 5R6 resistor.