74ls138 drive digital tube display design

Posted on December 26, 2022

74ls138 is a 38 decoder, which is a TTL series, that is, 74 series. There are three input terminals A0, A1, A2, of which A2 is high, the output is eight low-level outputs Y0 ~ Y7, and the working voltage is generally 5V.
74ls138 works:
1 When one strobe (S1) is high and the other two strobes ((/S2)) and (/S3) are low, the binary of the address terminals (A0, A1, A2) can be used. The code is translated at a low level at the output corresponding to Y0 to Y7. (ie, the output is not Y0 to Y7) For example, when A2A1A0=110, the Y6 output outputs a low level signal.
2 S1, S2 and S3 can be cascaded to expand into a 24-wire decoder; if an external inverter is connected, it can be cascaded to a 32-line decoder.
3 If one of the strobes is used as the data input, the 74LS138 can also be used as a data distributor.
4 can be used in the decoding circuit of the 8086 to expand the memory.
74ls138 drive digital tube display design decoder is an important device of combinatorial logic circuit, which can be divided into two categories: variable decoding and display decoding. Variable decoding is generally a device with fewer inputs becoming more outputs, generally divided into 2n decoding and 8421BCD code decoding. Display decoding mainly solves the conversion function of binary numbers displayed as corresponding ten or hexadecimal numbers, which can be generally divided into two types: driving LEDs and driving LCDs. Decoding is the inverse of encoding. When encoding, each binary code gives a specific meaning, that is, it represents a certain signal or object. The process of "translating" the specific meaning of a code state is called decoding, and the circuit that implements the decoding operation is called a decoder. In other words, the decoder is a circuit that can translate the state of the input binary code into an output signal to indicate its original meaning. The output signal can be a pulse or a high level or a low level as needed.

The schematic diagram of the 74ls138 drive digital tube display is as follows:

The 74ls138 drive digital tube circuit diagram is as follows:
74ls138 drive digital tube part of the program:

74ls138 drive 8-bit digital tube all circuits and programs share free download:>>>> 74ls138 drive 8-digit digital tube

USB Socket
Function description

The socket is ordinary converter,with two output 5V2A power USB power supply at the same time,can be very convenient in use electrical appliances and recharge the equipment at the same time,such as digital products like Iphone Ipad,MP3,MP4 etc.The charge apply to full range of international AC output,no-load power consumption less than 0.3W,with short circuit,overload,over-voltage protection,can be convenient for your life and save more energy

Timer Control Time Adgustment

1.Press the power switch 1 time,the 1HOUR LED will light on.The Timer into ON mode,USB and control socket output ON .

2.Continuously press the power switch the LED light on,the Countdown mode and LED light on will cycle change from 1HR,2HR,4HR,6HR,8HR,10HR.

3.Choose you need countdown time mode,the mode LED will lighto on,start countdown until countdown time finish,the control output and USB change to OFF

4.Then the countdown is start,The Time indicate LED will from high to low auto change until Countdown finish off.

Failure analysis:

1.check whether the power supply connection is good

2.check whether the USB cable is loosen

Warning Note:

1.Use indoor and dry location ONLY

2.The load max does not exceed 15A 3600W

3.This product does not convert voltage please do not miss use DO NOT exceed the maximum loading of 3600 Watts 15A

4.Always have earth connection for safety reason

5.If in doubt please consult with a qualified electrician
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