4 Channel IR Transmitter and Receiver Module Using ht12A & HT12d

4 Channel Infrared (IR) Remote is a simple project using the popular HT12A and HT12D encoder/decoder chips from Holtek.  The project can be used in latch mode or momentary mode, mode selection possible using J1 Jumper and transmitter end. All output at the receiver end is TTL.



  •     Supply – Transmitter: 2.4 ~ 5 VDC, 5 V @ 20 mA & Receiver: 5 ~ 6 VDC, 5 V @ 50 mA
  •     Output – 4 Latched/Momentary TTL compatible outputs
  •      Crystal based oscillator for the reliability of operation
  •      DIP switch selectable 8-bit address code
  •      LED output to indicate reception
  •      ON/OFF slide switch in the transmitter
  •      Power-On LED indicator in the Receiver / Transmitter
  •      High noise immunity
  •      Berg connector for interfacing of the board
  •      Four mounting holes of 3.2 mm each
  •      PCB dimensions – Transmitter: 61 mm x 47 mm & Receiver: 46 mm x 46 mm

Balanced Audio head-phone amplifier ( Balanced audio monitor)

Useful audio device for audio professionals, tiny board is a balanced headphone monitor, based on BA4560 op-amp, project works with 12V DC supply, Female XLR connector helps to feed balanced audio input, male XLR connector for parallel balanced signal output, and 3.5MM Stereo EP socket provided to connect headphone, easy supply input using standard DC socket, onboard potentiometer provided to adjust the gain.


  • Supply 12V DC
  • DC Socket for Supply Input Or CN4 Header Connector
  • 3.5MM EP Socket for Headphone
  • Load: 32 Ohms Headphone
  • XLR Female: Balanced Audio Signal Input
  • XLR Male: Balanced Audio Output
  • D1 Power LED


  • C1, C2 10uF/25V Bipolar Capacitors,
  • C11 220uF/16V , C10 470uF/16V, C1,C2 40uF/25V  Electrolytic Capacitors
  • All Other Capacitors and Resistors SMD 0805
  • IC BA4560 SMD SO8 www.rhom.com

High Precision Low Cost Adjustable Constant Current Source Output 0 to 2.5A

Current sources are widely used in industrial, power supply, LED drivers and other equipment. The project has been developed using the AD8276 difference amplifier and the AD8603 op-amp. Current source using the low power AD8276 difference amplifier and the AD8603 op amp are affordable, flexible, and is small in size. Performance characteristics such as initial error, temperature drift, and power dissipation make the AD8276 and the AD8603 ideal candidates for such project. The circuit provides current 0 to 2.5Amps, input supply 12 to 15V DC. I have tested this board with 4.7E/10W X3 parallel resistors.

Download PDF Schematic

Download AD8276 Data Sheet

Download AD8603 Data Sheet


  • Input 12 to 15V DC
  • Load Current Up to 2.5Amps
  • Current Adjustable 0 to 2.5Amps
  • On Board Trimmer Pot to Adjust the Current
  • Required Large Size Heatsink for full load 2.5Amps