#pic16f88

[jayakody2000lk]

This post describes our initial attempt to design an automatic Zener diode tester. This tester is designed using well-known ICs such as MC34063 and PIC16F88.

This unit is capable of identifying Zener diodes up to 27.5V. Apart from that, it can be used to recognize leads of the diodes/Zeners and detect damaged diodes.

For this project, we use components that are already in our inventory. Most of these components can be replaced with more accurate and modern substitutes.

This unit provides approximately 5% to 15% accurate readings. Based on our observations, the accuracy of this unit can increase by using resistors with 1% tolerance, stable booster circuit, accurate sampling method(s), and with a more optimized PCB layout.

The schematic, PCB design and firmware of this project are available to download at github.com.

[pauljacobevans]

Garage Distance Sensor Kicks Tennis Ball To Curb

Those with small garages might be familiar with the method of hanging a tennis ball from a ceiling to make sure they don’t hit the back wall with their car. If the car isn’t in the garage, though, the tennis ball dangling from a string tends to get in the way. To alleviate this problem, [asaucet] created a distance sensor that can tell him when his car is the perfect distance from the garage wall. At the heart of the distance sensor is an HC-SR04 ultrasonic rangefinder and a PIC16F88 microcontroller. [asaucet] uses a set of four LEDs to alert …read more http://pje.fyi/PdcDcn

[jayakody2000lk]

If you are an audio enthusiast and if you have multiple audio systems and speakers, you may definitely need to have a speaker selector switch. These switches allow you to route a audio signal through a switching system and distribute it to various speakers. Using this listener can select single amplifier – speaker combination through the switch. We mainly design this switch to share our speaker system with multiple audio amplifiers. We design this switch to handle 6 stereo audio channels.

This switch is based on PIC16F88 – 8bit MCU, ULN2803 Darlington transistor arrays and 12 DPCO relays. MCU is the core component of this switch and it control all relays, seven-segment display and store last channel in E2PROM memory and restore it during next power-up.

This speaker selector is an open hardware project, all it’s source codes and schematics are available to download at google drive and github.com. All it’s content are released under the terms of MIT and CC BY-SA licenses.

[jayakody2000lk]

6-channel speaker selector

At the beginning of 2018, we developed the first version of the 6-channel speaker selector using PIC16F88 MCU and ULN2803 Darlington transistor array. In this new design, we redesign it with low-cost MCU and Darlington transistor arrays. This design also provides the same functionality as the 6-channel speaker selector switch we designed earlier.

This new speaker selector uses STC15W201 MCU. This MCU is a low-cost 8051 MCU designed by STC micro. At the time of this writing, the STC15W201 can obtain for less than US$ 0.8. To drive the seven segments and to control the relays, this design uses the popular 74HC595 8-bit shift register ICs.

To select each speaker channel, we use pair of 12V DPDT relays. These relays interface to 74HC595 through a ULN2001D 3-channel Darlington transistor array IC. This 3-channel Darlington driver IC is functionally equivalent to the famous 8-channel ULN2003 IC. This ULN2001D version is an 8-pin IC and is available in both DIP-8 and SOP-8 packages. 

This new board is designed to work with a 12V DC power supply and in our prototype build, we use a 12V/5A SMPS unit to power the whole system.

To get the optimal results with this circuit, use an Omron G2R-2-12DC or an equivalent type of relay with a coil current lower than 100mA. 

The firmware of the STC15W201S is developed using SDCC. To flash the MCU, we use stcgal. Thanks to the built-in bootloader, we can program this MCU using a generally available 5V USB to UART module/dongle. 

The complete build process of the speaker selector is shown in the video below:

The functionality of the firmware is almost identical to the old PIC16F88 firmware. After powering up the system, the active speaker channel is displayed on the seven-segment display. To switch to a different speaker channel, press the button repeatedly with short intervals. 

To mute or disconnect the current speaker channel, press and hold the same button for more than 3 seconds. 

As described above, all functions of this circuit can be the control using a single push switch.

The PCBWay sponsored this project. PCBWay offers high-quality PCB manufacturing and assembling services. Also, they offer CNC and 3D printing services. The Speaker selector PCB is available to order from PCBWay. Check out the PCBWay website for its manufacturing capabilities and pricing.

This project is an open-source hardware project. All its design files, schematics, and firmware source codes are available at Github.com. 

The PCB design, schematic, and other design files of this project are covered with a CERN-OHL-W 2.0 license. Firmware source code is released under the terms of the MIT license.