Broadband amplifier based on 51 microcontroller

This design uses the variable gain wideband amplifier VCA810 to increase the gain and expand the AGC control range, and uses software compensation to reduce the step interval of the gain adjustment and improve the accuracy. The input part uses a high-speed voltage feedback op amp 0 P A842 as a follower to increase the input impedance, and a protection circuit is added to the input part without affecting performance. Various anti-interference measures are used to reduce noise and suppress high-frequency self-excitation. The power output part is made of discrete components. The passband of the entire system is 4.4 k Hz ~ 8.4 MH z, with a minimum gain of 0 dB and a maximum gain of 70 dB. The gain step is ld B/6dB/arbitrarily set. The error between the preset gain and the actual gain below 60 dB is less than 0.2 dB. The effective value of the undistorted output voltage reaches 10.1 V, and the AGC control range is 52 dB when outputting 4.5 ~ 5.5 V.

Schematic PCB

Implementing ultra-low-cost dual fiber optic network card 100BASE-FX based on Raspberry Pi microcontroller (open source software and hardware)

The Raspberry Pi microcontroller itself does not have an Ethernet MAC, but it can be easily implemented through the programmable IO of the Raspberry Pi. The programmable PIO of the Raspberry Pi microcontroller that costs 5 yuan a piece is indeed a miracle, with IO below 250MHz. Control everything.

Schematic PCB

Filter circuit (various design solutions + schematic diagram).rar

Filter circuit (various design solutions + schematic diagram)

Schematic PCB

51 microcontroller control example of RTL8019 Ethernet (original program + schematic diagram)

51 microcontroller to RTL8019 Ethernet control example (original program + schematic diagram).

Schematic PCB

UDP test based on STM32 and network chip W5200

UDP test based on STM32 and network chip W5200

Schematic PCB

Network card driver and LWIP protocol transplantation program source code for Ethernet communication module based on LPC2138 and DM9000AE

The network card driver and LWIP protocol transplant program source code for the Ethernet communication module based on LPC2138 and DM9000AE written by myself.

Schematic PCB

2019 Electronic Competition Question E-Internet-based signal transmission system (Xidian University)

Schematic PCB

Gigabit Ethernet PHY and PC point-to-point communication procedures and corresponding tests

The physical layer data sending and receiving of a PC is very simple. As long as one condition is met, that is, the CRC check of the data packet is correct, the network card can send the data packet to the application software. Otherwise, the network card will directly discard the data packet, which cannot be caught by any software. to the data packet.

Schematic PCB

555 timer: 4MHz (80 meter band) CW transmitter

Might not be an actual working transmitter, but it does produce a few mW of RF power at 4 MHz using only two LMC555s.
Principle of Operation (see attached simplified schematic):
At lower operating voltages, the flip-flop (TR) input of the LMC555 can be used as an inverting comparator input to control the output of the device. This requires the Threshold (TH) input to be active (high). This circuit applies a DC bias at the switching threshold of TR and superimposes a small AC feedback signal to create an oscillator. An inverted version of the same signal is applied to the second LMC555 to produce two complementary open collector outputs (the device's discharge output). The output is then connected as a standard push-pull RF amplifier. The TH input is used as the enable input to key the transmitter.

Schematic PCB

10.5GHz (X-band) patch antenna

4 Layers PCB 60 x 171 mm FR-4, 1.6 mm, 1, HASL lead free, Green Solder Mask, White silkscreen;10.5GHz, 8 element, patch antenna. Make your own phased array for communications or radar. Full instructions at github .com/jonkraft

Schematic PCB

FPGA-based Ethernet controller (MAC) source code

Schematic PCB

2021 Undergraduate Electronic Design Competition Title E National Second Grade Work (Digital and Analog Signal Mixed Transmission Transceiver)

Schematic PCB

WS281x LED RS485 transceiver

2 Layers PCB 10 x 18 mm FR-4, 1 mm, 1, HASL with lead, White Solder Mask, Black silkscreen;Cofigurable RS485 TX-RX transceiver for long range serial LED strip communication

Schematic PCB

ZTE 2400-48V50A communication power supply schematic diagram

ZTE 2400 48v50a circuit schematic diagram, available for maintenance

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RTL8111E+RTL8105E application reference schematic

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51 microcontroller TCP-IP+ protocol stack ZLIP source code

Realizing network communication using limited resources on 51 microcontroller platform

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EtherCAT communication development platform based on ARM processor-schematic diagram

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EVALZ-ADN2905/EVALZ-ADN2913/EVALZ-ADN2915/EVALZ-ADN2917 User Guide

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Evaluation kit based on Si5328 any-frequency precision clock timing IC Si5328-EVB

Schematic PCB

AD9684 Evaluation Board for Sampling Wide Bandwidth Analog Signals

Schematic PCB