Useful cheap small tester...

[milairuk]

Regarding the display - don't get too hung up on that - they are easy to change - the normal standard is for an interface known as H44780 - most generic LCDs offer this interface and I deeply suspect this one is no different - there is one other interface, but its not common. If you want to change your green-no-back-light display to a blue one, then its VERY cheap to do so , e.g. http://www.ebay.co.uk/itm/400458908216

Thanks Nick,

£0.99 + £0.55 postage - how on earth do they do it !!

John

[Joe]

Mine's back-lit but not blue. I can't say it bothers me as I'm not likely to use it in poor light.

- Joe

[camallison]

Readers may recall I also bought a Warf transistor tester before one of these. The display on that doesn't have a back-light and, after taking delivery of the small tester with backlight, I immediately modified the bigger one. It was a simple mod, taking a supply and logic signal through a MPSA 14 darlington transistor to a specific connection on the display board (pin 15 IIRC) and now it has a the backlight. The display board is very similar to that one the small tester has and so the facility is possibly available with a bit of judicious probing.

On the modifed board, I connected pin 16 to ground, emitter of the transistor to pin 15 and collector to battery positive. When the display turns on it produces a logic high which in turn switches the backlight on via the transistor.

Colin

[Yorkie]

Regarding the display - don't get too hung up on that - they are easy to change - the normal standard is for an interface known as H44780 - most generic LCDs offer this interface and I deeply suspect this one is no different - there is one other interface, but its not common. If you want to change your green-no-back-light display to a blue one, then its VERY cheap to do so , e.g. http://www.ebay.co.uk/itm/400458908216

Thanks Nick,

£0.99 + £0.55 postage - how on earth do they do it !!

John

Obviously they benefit from economies of scale, but whist they're into manufacturing in a very big way, they seem to not have embraced the concept of marketing or they'd charge more - especially for one-off sales. The price at which something is sold does not need to be based on what it cost to make, but on what the market will stand. I'd suggest that the market would stand at least four or five times that being charged for this display, and at 55p post, it's only 5p more than a UK second class postage stamp.

So it's not just a question of 'how' do they do it, but 'why' do they do it? On e-bay they're selling to a world market - mainly I guess the West - UK, USA, Europe etc where few would expect to pay only the price of a newspaper for such a display, but as with all such stuff from the orient, it's to our good fortune that they're so cheap.

[Eddystonepete]

Hi All, thanks for all the info on the chinese tester, remarkable piece of kit, pity the inductance ranges dont go down further. I like die cast boxes, so I ordered the 111mm long one from RS, an almost perfect fit. I forgot about the corner "buttresses" that the screws go into. I managed to gouge and grind (and that was using an ML7!) bits out of them to accomodate the main board even then had to cut the corners off the board. Finished job looks neat but to anyone else trying the DC box route, its a bit fiddly.
Peter

       

[Joe]

Nice job.

- Joe

[camallison]

I managed to get hold of one of the enclosures shown in the attached picture. Obviously, I will be putting my own front panel "decoration" on. It is quite handy in that it has a battery compartment that takes a PP3 battery. Just waiting for the current winter weather to abate before venturing out into the workshop to drill and cut it.

Colin

[Nick]

As I had a few minutes in the shack, I checked my one of these - I speculated that it was a standard Hitachi HD44780 interface, which it is.

The LCD module on my unit is a Shenzhen Eone Electronics 1602A with a Sitronix ST7066U character-mode controller - the ST7066U is HD44780 pin-for-pin (electrically) and also byte-for-byte (software) compatible.

If you have a non-backlit display, any HD44780 compliant 2 x 16 character display will do - blue/green/orange/white whatever...

I've attached both data sheets to this reply...

HTH

[Skywave]

I've recently bought one of these, and doing a quick test, yes, it works.
All the above posts in this thread will be very useful to me: thank you all for those posts: very informative.

So, now for a suitable box . . . etc., etc.

Al. / 24 Sept. 2013. //

[Skywave]

Suitable aluminium box found; project built. My initial comment: "Yes, it works" was only a quick go/no-go test. But now two 'features' have raised question marks in my mind:

(1) The display, prior to timing out, is too short: I get about 5 seconds.
(2) When the display does state 'time-out!", it doesn't switch itself off.

Does anyone here have any suggestions how those two 'features' can be improved, please?

P.S. There is no backlight - but that is not a problem.

Al. / Sept. 26, '13 //

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Edit, Sept. 26, 2013: photos.:

[attachment=9094] [attachment=9095]

In terms of overall assembly and presentation, not the neatest item I have assembled, but it meets its intended purpose.
The three terminals are the spring-loaded Eddystone Radio type.

Al.