LM3900 | Electronic Project Circuits

Posts Tagged ‘LM3900’

Temperature monitor

This temperature monitor circuit is used where a continous analog display of temperature value being monitored is not necessary. A simple indication whether the temperature value exceeded a maximum level or went below the minimum level is sometimes enough. The circuit here does just that, it indicated the temperature level about +25oC (77oF) or below +20oC (68oF) by lighting one of the two LEDs.
The temperature sensor is an NTC resistor coupled to two comparators. When D3 lights, the temperature is above +25oC and when D2 lights, the temperature is below +20oC.
Temperature monitor calibration
Place the NTC resistor in cold water. Slowly heat the water until the desired maximum temperature level is reached, then adjust P1 until D2 lights up.
To set the minimum level, stop heating the water then slowly add cold water to it until the desired lower temperature level is reached as indicated by the thermomter. This time adjust P2 until D1 lights up.
The Author Name: P. Marian
Source:http://electroschematics.com/6205/temperature-monitor/
This is good site thank you.

Be the first to comment - What do you think? Posted by admin - May 8, 2011 at 9:35 am

Categories: Meter Tags: LM3900, temperature monitor, temperature-meter

Two Tone Alarm generator using LM3900

This circuit use 2 beep danger sound origins. By use the integrated circuit LM3900 just one. Which compose OP-Amp 4 group stay within the integrated circuit and have , Mosfet , give -ing the sound with 8-80 ohm small-sized loudspeakers s by use , power supply 9V sizes will arrive at 12V may are battery 12 Voltage all right. For other detail have a few the equipment a little also, request friends have fun this circuit.

Be the first to comment - What do you think? Posted by admin - December 12, 2008 at 9:06 am

Categories: Alarm systems, Audio diagram Tags: alert alarm, LM3900, Sound Alarm Generator

OTL Amplifier 60W by LM3900

This is power amplifier OTL circuit,It is old but good amp(classic) I like it.
It is have power output 60W at 8ohm speaker.
I use IC op-amp LM3900 is mian part in this circuit.
The LM3900 function amp audio signal,ad have transistor 2N3055 x3 for boost power sound audio.

The voltage power used 70V at 3A min.