Sunday, 27 November 2016
Bought this mini oscilloscope as a kit on eBay (from China as usual) for £20. The main board with the surface mount components was already completed, but the electrolytic capacitors, an inductor, diode and all the switches had to be soldered in along with the display. There is no case as such, but clever use of 2 extra pieces of pre-cut PCB and 4 stand-off fixings make for a nicely finished unit. I might make sides for it out of 3mm foam board if the notion takes me.
When I initially switched it on, nothing much happened except the backlight was on. Checking the troubleshooting guide helped and it turned out that the potentiometer for adjusting the LCD contrast needed a bit of working up and down to clean its track.
The 'scope can measure up to 2 MHz which is fine for my needs and has sample and hold and a frequency meter function. I tested it with the composite video signal from my Arduino TV-Out board and got a nice sync waveform at the right frequency.
More information at - www.jyetech.com
Friday, 25 November 2016
This is the second of these little black and white televisions I've picked up. I think my wife got this one in a charity shop in Portaferry (for £3 if I remember right). They run on 12 volts or a load of batteries and have a radio as well as TV.
Anyway, a bit of Internet research revealed that all of the RF side of TV things is handled by a single chip and the composite video is dealt with by old-school transistors. This made it easy enough to cut into the video circuit at the right point and hook it up to the DVD player and we have a retro composite monitor.
The radio section was on its own board which I removed along with the speaker, front panel switches and so on. Some plastic card to fill the gaps, epoxy and satin black paint gave it a bit of 80s class! I also added a power LED to the front and re-wired the antenna jack socket to act as the video input.
The DVD player is actually a recorder I got on Freegle because the power supply had packed in. In this case the transformer had fried, maybe due to a shorted 'bad cap', so I replaced the whole power board with a similar one from another broken DVD player. A bit of drilling and soldering and it is working like new. It would make a great CCTV security recorder.
Sunday, 11 September 2016
My wee lad's Zoostorm tablet (Q6010) seems to have gone into limp mode, as in limp to the spares box. It has gotten locked into some sort of unresponsive state where the touchscreen isn't working and pressing the reset button or any of the Android reboot sequences does nothing. It was a strange tablet from the start, aimed at the education market and with a weird storage partition layout, but a quad core processor and a whopping 2Gb of RAM which 2 years ago was unheard of. And all for under a ton from CPC. The pity is that it runs Android 4.2.2 (JB) so could in theory be used as a Kodi box, but only if I can get it to work again. In the meantime, good dad that I am, he's getting my old Fujitsu M835. Back to paperback books for me then.
Friday, 26 August 2016
Saturday, 23 January 2016
I was going to say 'repair', but really this is an upgrade. My son's Android tablet stopped charging and pretty quickly we tracked the problem to the power supply cable. This didn't surprise me because it was a pretty cheap bit of cable, speaker wire really and I always thought it wouldn't last. The tablet itself is a bit of an oddity, a Zoostorm educational tablet with 2gb RAM and a quad core processor, but it was being sold by CPC a year ago for under £100. The reason may be the odd OS customisation with a strange storage layout almost certainly set up for school use, but we have tackled that and Need For Speed runs just fine on the device!
I tried reusing the moulded DC plug, but it shorted out so a trip to Maplin got me a replacement for £2. It is the smallest plug in the range as it happens. Looking at the cable, I thought I might as well do the job right so a delve in the spare cables box turned up a nice heavy wire from a defunct power supply for something else. Once again heat shrink sleeve came to the rescue to make a strain relief for the plug and the join to the stump of the old cable at the power supply end, and make the whole thing look nice and neat.
Better than when it came out of the factory!