Finding 3-phase is difficult, convincing the owner of the said supply to test some home made hardware is even more so. After building a 3-phase energy monitor my testing options for it appeared very limited. So I set about making my own low-cost 3-phase energy monitor calibration system.
As I read many pages on the internet I saw there is a sort of adapter so called “USB to TTL adapter” who can communicate through with the uC. I had not the time to order one but I give a try to make one for the COM port. Actually it is an RS232 to TTL converter which I found better from my opinion than that USB to TTL adapter.
Here is why I like more this RS232 to TTL adapter than the other one:
can be used on a real RS232 port
it is a stable voltage level converter
can be used on USB port too (through USB to RS232 converter)
there is no VCC ( somebody would say it’s a disadvantage but wait…) *
it is a real hardware stuff, no emulation etc. (if it is used through a real com port)
Kerry Wong built a DIY battery bank using eighty 32650 LiFePO4 cells:
During the past couple of weeks I have been busy making a large battery bank using the eighty 32650 LiFePO4 cells I bought on eBay. The battery bank I am building is a 12V (13.2V nominal) 4S/20P one. With each cell rated at 5.5Ah the battery bank has a capacity of 110Ah, which is just under 1.5kWh.
While These cells are marked as 32700 they are technically still 32650 cells according to the datasheet, which is a little bit confusing. Since I am making a custom battery bank the actual cell dimension is not as critical.
Inspired by an old article from sparkfun and some tests I conducted myself I came up with a PCB that holds the pogopinholders and an lasercut acrylic fixture for the PCB on top. Using the dirt(y)cheap services from dirtypcbs.com the cost for this jig, including pogopins and their holders is about 45 USD. As an advantage you receive 5 lasercut acrylic and 10 PCBS which allows you to make 3-4 jigs in total!
To design the PCB that holds the pogopins I started with a 10×10 PCB with M3 mounting holes and imported the to be programmed PCB (File, Import, Eagle drawing) and place this in the centre (not mandatory, but looks prettier).
Dilshan Jayakody writes, “This is an automatic Cat6 / Cat5 network cable tester designed using NE555 timer and 4017 decade counters. This unit test all 8 wire lines of twisted pair network cable and indicate pass/fail status with single LED. We design this unit to test network connectivity issues in Cat6 / Cat5 cable systems and it is capable to check both crossover and straight-through type network cables.”
My Xi 8088 homebuilt PC is running a little short on slots, so I wanted to combine the functions of a game control adapter and an 8255 PIO board. Two functions in one slot. As to why one wants each of these things:
A game control adapter is used to interface to PC joysticks. These are the old-style analog joysticks with the 15-pin connectors.
An 8255 board is a general purpose interfacing board, providing 24 bits of digital IO that can be configured as inputs, outputs, or a mix of both. This is not in and of itself a “parallel port”, but could probably be used to implement one.