A project has been designed around Holtek,s HT8970 voice echo IC. Project can be used in various audio systems karaoke, toys, Animatronics, shows, displays, exhibitions, and sound equipment’s. The HT8970 is an echo/surround effect processor. It is designed for various audio systems including karaoke, television, sound equipment’s, etc. The chip consists of a built-in pre-amplifier, VCO or Voltage Control OSC, 20Kb SRAM, A/D and D/A converters as well as delay time control logic. The HT8970 chip echo processor IC utilizing CMOS technology. Which accept analog audio input signal, a high sample rate ADC transfer the analog signal into a bit stream then storage to internal RAM, after processing the bit stream will de-modulate by DAC and low pass filter. Overall delay time is determined by internal VCO clock frequency, and user can easy to change the VCO frequency by trimmer pot. Jumper J1 provided to select the Microphone input or External audio signal input, CN1 Audio Signal input, PR1 Audio signal level adjust, PR2 output audio signal adjust, PR3 sound delay adjust,
DOWNLOAD DOCUMENT AND SCHEMATIC
DOWNLOAD PDF DATA SHEET HT8970
- Supply Input 5V DC
- Onboard MIKE and Aux audio input ( Dual Option Selecting using Jumper)
- MIKE and Aux Selection via jumper
- Input/MIKE signal level adjustable using Trimmer Potentiometer
- It works in two modes – echo or surround
- On Board Output signal level adjust Trimmer Pot
- Onboard Trimmer Pot for Sound Delay Adjust
- Onboard LED for Power Supply Indicator
- Four mounting holes of 3.2 mm
- PCB dimensions 79 mm x 70 mm
The sensor project is based on AD595 IC from Analog devices. AD595 is a complete instrumentation amplifier and thermo-couple cold junction compensator on a monolithic chip. It combines an ice point reference with a pre-calibrated amplifier to produce a high level (10 mV/°C) output directly from a thermo-couple signal. Pin-strapping options allow it to be used as a linear amplifier-compensator or as a switched output set point controller. It is amplify its compensation voltage directly, thereby converting it to a stand-alone Celsius transducer with a low impedance voltage output. The AD595 includes a thermo-couple failure alarm that indicates if one or both thermo-couple leads become open. The alarm output has a flexible format which includes TTL drive capability.
NOTE : Refer AD595 Data sheet for supply input and other information, The circuit works with single supply, same board also support AD594 IC which can support type J sensor.
- Supply 15V DC
- Supports Type K Thermocouples
- Provides 10 mV/Centigrade
Download PDF Schematic
What is Thermocouple??
A thermocouple is an electrical device consisting of two dissimilar electrical conductors forming electrical junctions at differing temperatures. A thermocouple produces a temperature-dependent voltage as a result of the thermoelectric effect, and this voltage can be interpreted to measure temperature. Thermocouples are a widely used type of temperature sensor
What is Type K Thermocouple Sensor??
Type K Thermocouple (Nickel-Chromium / Nickel-Alumel): The type K is the most common type of thermocouple. It’s inexpensive, accurate, reliable, and has a wide temperature range. Type K thermocouples usually work in most applications as they are nickel based and exhibit good corrosion resistance. It is the most common sensor calibration type providing the widest operating temperature range. Due to its reliability and accuracy the Type K thermocouple is used extensively at temperatures up to 2300°F (1260°C). This type of thermocouple should be protected with a suitable metal or ceramic protection tube, especially in reducing atmospheres. In oxidizing atmospheres, such as electric furnaces, tube protection is not always necessary when other conditions are suitable; however, it is recommended for cleanliness and general mechanical protection. Type K will generally outlast Type J because the JP wire rapidly oxidizes, especially at higher temperatures.
Type K Thermocouple Range
- Thermocouple grade wire, –454 to 2,300F (–270 to 1260C)
- Extension wire, 32 to 392F (0 to 200C)
AD595 Output Voltages
Various Type K Temperature Sensors