Posted by on August 9, 2011
The differences between them are:
Turns out you can enable the RS232 interface by shunting pin 84 to GND, you will then obtain the data through pin 64 which is TX.
Originally pin 64 would drive the base of a PNP (2n3906) which in turn would drive an IR LED, this LED provides optical isolation — Typically there would either be an external plug-in module with a photo-transistor or it would have the module built-in, with the connector exposed to the user.
My suggested modification would only require a small hole at the back of the enclosure to expose the LED, you could then interface with it rather easily.
True-RMS cannot be “unlocked” easily since this feature requires an extra IC (AD737 or similar) which obviously isn’t populated on the C version. Other components around this IC are required as well.
I’m not sure but perhaps the quiescent current would increase if you have the RS232 mode enabled, it may be worth testing.
For a protocol specification you may refer to the FS9721 LP3 datasheet, even though it’s in Chinese you should be able to comprehend most of it. Scroll near the bottom to find the RS232 section.
Either way, if you have the UT60C and you wish you had data-logging capabilities, give this a go — You don’t have to make any permanent changes if you only intend to test it.
Posted by on August 4, 2011
Here’s a XBOX 360 USB SPI Flasher with a Mini-USB connector, the board is based on this project.
I redesigned the PCB since the original had a poor layout and used quite the uncommon B type connector.
It was made for a friend but I’m sharing it nonetheless, you can see his results here (Don’t worry, the whole “xbox sucks” deal is an inside joke).
You can download the eagle sch and brd files from here: Xbox360 Mini-USB SPI Flasher.
In theory the board could be made smaller, but since most people will be making these at home, I decided to use a bigger isolation gap, bigger pads, etc. To simplify the process.
For reasons of availability the smd switch was replaced by a simple pin header, thus a jumper is used instead of the switch.
Posted by on June 21, 2010
Most alarm clocks run their internal clock oscillator off of the mains frequency by detecting the peak on each cycle and thus
obtaining their timebase. However not every country uses the same grid voltage/frequency! — This poses a problem, if you’re using a 60hz clock on 50hz, it’s going to run at ~83% of it’s intended speed!
I’ve seen three types of clocks so far, the ones that automagically detect the mains frequency, the ones that allow you to choose with a simple switch, and those that just won’t run at your mains frequency!
For the latter, the following applies: Continue reading “Changing the timebase on a cheap alarm clock.” »