Posts tagged: hacking

Jul 20 2012

Identifying meaning of “HD” pin on LCD viewfinder

I’m aiming to finally build a wearable, and managed to find a cheap alternative to cutting a set of video glasses in two for a monocular. I got a broken analogue video camera off ebay that had a colour LCD viewfinder. It was a bit of a gamble that being analogue it would have simpler inputs than a digital camcorder, but it paid off. I received the camera today, pulled it apart and got it running on it’s own. 0.2A @5v with composite PAL input.

There’s a 4th pin on the connector though, in addition to Gnd, 5v and video. It’s marked “HD” on the viewfinder PCB, and I traced it back to the IC where (after going through a SMD transistor) connects to the “HD” pin 30 on the controller IC.

The datasheet for the IC expands it a little that the HD pin is for “HD pulse output”, but I can’t find anywhere that explicitly states what the HD pulse is.

I’m *guessing* it’s something to do with the frame timing since the only other HD I can find in the sheet relates to “Horizontal Direction”.

The IC is a Sony CXA1854AR by the by.

The camera supplies the HD pin on the connector with 4.3v however, or at least seems to. I thought I tested it for voltage with the display disconnected, but I’m not sure now. Rather sleep-deprived.

In any case I’m thinking it’s either a case of the IC pin using the transistor to pull the connector pin low, or more likely now that it’s actually a 5v output and my multimeter detected it at only 4.3v due to the duty cycle of the HD pulse. The HD pulse presumably would be something to sync with the video or on-screen text display. But it seems to display PAL video with no problem when it’s not in use, so unsure.

Really I’d just like it if someone can put my mind at ease on the subject. It doesn’t seem essential, but I’d like to know what it’s supposed to do.

Jul 29 2010

Making new photographic lamps

One issue I’ve had with both taking photos of people and close-ups of items is the lack of light. A couple of small halogens really doesn’t cut it, so I’ve been thinking over affordable and adaptable replacements.

I picked up a couple of clip-on lamp holders cheaply from EFG Housewares, a wholesaler I use for some of my shop supplies. I wanted to get some simple reflectors for them, but couldn’t find any at a reasonable price online. Even simple one-piece pressed aluminium shades seem to carry excessive prices. So it was off to the 99p Shop in Walthamstow High Street, where I found a couple of suitably shallow 30cm cheapo stainless bowls.

I next borrowed one of my dads Q-Max sheet metal punches. They’re very nice and provide a clean hole in sheet metals very easily.

I used a 30mm punch, but really should have used a 28mm or so. I measured from the inside of the lamps collet, not the thread. Whoops. But that’s alright in the end. I used my home-made centre-finder to mark out the bowls. It finds centre well on circles, but I also forgot the pegs on it weren’t the same length, so on the bowls curves sides it skewed the centre. So the error on one was enough in the end to correct for the error on the other! There’s a lucky break, eh?

Next up, a 10mm hole is drilled so the bolt of the punch can go through. The bolt is tightened and pulls the cutter into the punch block from the other side of the metal.

Voilà! A nice clean hole! (can’t say the same about the bowl)

I took some burrs off with a hand file and did the other bowl to match, then took them back indoors to fit the lamp holders to them.

Next I ordered some energy-saving high-brightness “daylight” bulbs off ebay. It took a few more days and a trip to the sorting office, but I got them this morning.

They’re 36Watt (180Watt equivalent), rated at 2160 Lumens, an 8000Hr lifetime and a colour temperature of 6500! They’re also wide mushroom-shaped coils, so should give a fairly diffuse light with no harsh shadows.

Without new lighting

With new lighting

And finally, fitting them they work perfectly. I was a bit worried the light would be too directional, but it’s both bright and pleasantly diffuse. I’m sure my opinion will refine the more I use them, but for the moment I’m pretty happy with the results!

(auto-exposure doesn’t like looking directly at them when they’re on)

Total cost:
Lamps – £1.65 each (Total £3.88 inc VAT)
Stainless bowls – 99p each (£1.98)
Lamps – £4.29 each (Total £12.06 inc Postage)

TOTAL: £17.92

That’s about the same as for a single studio lampshade. A complete lamp runs to about £50.

Jun 29 2010

Eye-Fi and mobile phones – instant remote backup of photos?

When I first heard about the Eye-Fi SDHC a couple of years ago, I was very intrigued, but saddened that it seemed so locked in to one service. But time’s gone by now, and it looks like they’ve opened their doors a lot wider.
The Eye-Fi is an up to 8Gb SD card with a built-in 802.11n wifi functionality. The idea is that when a photo is taken, it’s stored and also uploaded by any open wifi point to the web service. And now there’s a number of services including YouTube, but more importantly I feel, the open-source Gallery 2. The Gallery 2 option means it can now upload to your own personal webspace, located in the country and legal protections of your choice.

However it still requires you to get within 27meters (max) of an open wifi point. And with the spectre of an un-redacted Digital Economy Act looming, open wifi points may soon become rather thin on the ground.

However, one of the things that came up in the original discussion of the Eye-Fi was the idea of using a data-enabled SmartPhone with wifi as a bridge. Eye-Fi talks to your phone via 802.11n, phone talks to the internet via 3G or other mobile broadband. It’s a delightfully simple and compelling concept, but one that has apparently seen little development. Perhaps I’ve simply not found it yet, but it’s hard to find discussion of the subject past 2007.
Certainly you could use a laptop for the same purpose, but that shouldn’t be necessary, particularly as open-source phones such as the Android now exist, where the necessary programming should be relatively simple. And in any case, the uptime comparisons are unlikely to favour it.

In a world where police can illegally demand or force you to delete the video and images from your camera, I for one would treasure the warm inner glow from knowing that while the originals are gone, identical copies have already transferred to my phone and on to a secure server on the other side of the planet.

So if anyone knows of a bit of software to turn your SmartPhone into a passive wifi access-point/bridge, I’d love to hear about it, as I’m sure others would.

Apr 18 2010

Power, lathes, wings

Reprap prototype PSU is done and ready for the stepper controllers to arrive now. All boxed up nicely. If memory serves, it didn’t have a fan when it was in the fax machine, so should be fine in the enclosure. At worse I might have to drill it some extra air holes.
Mains lamp, some (vintage) terminal posts, switch and IEC C14 socket.

Even took the engraver to the front panel to mark out the various terminals and added a couple of ferrite beads to the lines to be on the safe side, and used some cable wrap to keep the wires tidy.

Today I also finally removed the piston and cam off the old compressor pump, and filed down a pully to fit. I’ve hooked this up to the 3rd party headstock from the Black and Decker extruded aluminium wood lathe I found last year. It’s meant to be run by a type of drill they no longer make, so the compressor motor should be easily powerful enough. Currently getting a head speed of about 3200rpm, so it’s currently about twice as fast as it needs to be. Will see about swapping the headstock pully for something larger (I have one, but getting the old one off will be a pain).
It’s not urgent, but it’s sitting around and there’s a friend who should be able to use it once it’s basically working.
Also made a control box for it, currently a simple latching safety power switch (see background of first image) from a broken garden shredder and an old RS project box. If I find a spare suitably rated rheostat I may add a limited speed controller.

Also the sewing for the set of “Navi” wings was mostly done today, but one of the blue plastic rods snapped while trying to flex it into it’s “pocket”.
After some considerable swearing and therapeutic angle-grinder time (see above compressor pump), I will tomorrow attempt to construct a coupler out of clear perspex rod and use it to join the two broken ends, as the stress on them will likely be more than any other repair would take. this may mean purposefully breaking and repairing the opposite wing to match.

[20/06/2010: Amalgamating old posts from “Dreamwidth Creative Blog” into to re-purpose DW blog account.]

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