Good explanation of code hopping

The article on page 23 of the July 2002 issue of SILICON CHIP entitled "What is Code Hopping" is one of the best descriptions of rolling code chips that I have read so far.

I am an automotive locksmith, trying to inform other auto locksmiths, so this article will be very useful.

B. Williams,
Kogarah, NSW.

XYZ table project wanted

Has the "XYZ Table with Stepper Motor Control" project described in the May to October 1999 issues of SILICON CHIP ever been available as a complete kit, short form kit or fully built up from any supplier? Perhaps there is a complete project or an unfinished one gathering dust in someone's shed or workshop. If so, I would be interested in purchasing one.

Andrew Court,
93 Norana Rd,
Upper Hutt, NZ.
email: ajcourt@ihug.co.nz

Table AM/FM radio sounds desirable I've just been reading today's edition of "The Green Guide" in The Age newspaper. In it there is an advert and article about "the new Henry Kloss Model One AM/FM table radio". The article highly praises this radio and implies that plenty of them are being sold. It is quite an attractive looking radio in a wooden case and sells for $299. There are three styles of cabinet available. It occurred to me that a similar radio may be able to be designed locally and offered as a kit at a (hopefully) lower price. The radio would need to be in a good-looking wooden case and with a decent output stage and speaker. B. Freeman, Morphett Vale, SA. Comment: in practice, it would be very difficult for us to design such a project at a price that would be viable. However, there is another approach and that is to build a standard 12V car AM/FM radio/tape player into a timber case together with two speakers and a suitable power supply. Such a radio will give very good performance and is bound to be much cheaper than $299. We showed how to do this in our very first issue, November 1987.

Passive preamplifier works well

I'd just like to offer my sincere thanks to Sam Yoshioka for his excellent phono preamplifier with passive equalisation design, as published in the July 2002 edition of SILICON CHIP. I have built the preamp and I find its performance is absolutely superb. I find it quiet, open and utterly musical. My LPs have never sounded better.

By the way, can anyone tell me why record scratches, clicks and pops are now not so obvious? And it's not due to high frequency roll-off either.

I have always had a belief in the musical virtues of passive equalisation over the more common op amp feedback loop arrangement and I believe that the open, unstressed sound of Sam's design reflects this. A highly recommended circuit.

Felix Scerri,
Ingham, Qld.

Solar tower of power What an interesting article in the July SILICON CHIP, "Solar Tower of Power" by Sammy Isreb. For Australia, with lots of sunshine and open space and with a peak load in summer, this is perfect. In New Zealand, where I live, the peak power use is in winter. I look forward to a possible follow-up article. As a glider pilot from way back, I am aware that on a sunny day there is enough rising warm air from a dark-coloured ploughed paddock in an expanse of lighter-coloured growth to make your aircraft suddenly climb when you fly over it; ditto the large dark roofs of industrial buildings. So, I was wondering why the grass was left under the prototype solar tower in Manzanares, Spain (see photograph, July 2002, page 8) when presumably a layer of dark asphalt under the "greenhouse" would make the air hotter. Perhaps better, why not have a huge concrete block painted matt-black covering the entire area enclosed by the greenhouse roof? (Big concrete blocks were used in the "nightstore" heaters of some years ago in NZ to retain heat from cheaper, off-peak power). Then you wouldn't need to use water as proposed in the article to even out the day/night power generation curve of the solar tower and concrete can't "leak out" and won't corrode its self-provided "container" (the ground). Don't get me wrong, I think the solar tower idea is an elegant idea as it stands. As the article says, the Solar Tower technology is just "a step" in the right direction and I hope it happens. Stan Hood, Christchurch, NZ.

Suggestions for projects

I recently rekindled my appreciation of electronics and started buying SILICON CHIP magazine again. Some of the projects are great; eg, the camera in the drain pipe, however some are mediocre. As I have been out of the game for a while, I am a bit hesitant to tackle some ideas I have for projects. May I suggest the following ideas:

(1) An overvoltage and/or over temperature and surge protection circuit for the supply rails of PC power supplies (mostly now made in China, where quality control seems to be non-existent).

I have noticed in my work several times a year that I need to replace customer PC power supplies. Usually, the capacitors blow themselves to bits and occasionally a dangerously higher than expected voltage appears on the 5V and 12V rails, thereby taking out the motherboard, CPU, HDD, etc. One faulty capacitor takes out the whole PC!

(2) An over-temperature monitor for laptop PCs. I have come across more than one instance where the fan bearings dry up, the CPU and surrounding motherboard get cooked, and the laptop is useless. The repair cost for these replacement components is prohibitive and what was once a good laptop is now on the scrap heap. You have one disappointed customer who can't understand how an $8 fan can ruin a $4000 laptop!

(3) A piezo/strain/weight gauge for use in weighing your horse float, trailer, builder's ute, etc (one wheel at a time). You could take it with you to the soil/gravel/landscaper's yard and check your weight before you drive home. The road authorities are now pretty strict on what your vehicle can carry and there are many instances where people just haven't got the foggiest idea of how much weight they are carrying on or behind their vehicles.

(4) A degaussing wand for TVs and video monitors.

Shane Dwyer,
via email.

IR interference from compact fluorescent lamps

I just thought I'd drop you a line about what I found out after I built two kits. I initially built the MP3 Jukebox in the September & October 2001 issues (nice kit!) and found programming the keys a bit tricky, getting different codes if I held the remote button down too long. This was annoying but it still worked.

However, after I built the recent IR controller kit (SILICON CHIP, February 2002) to turn on 10 different appliances, I noted that the signal received LED was continually flashing. This was weird since to my knowledge, there was no other source of IR.

Then finally it dawned on me that the older TV and vacuum cleaner which both have IR controllers also operated in an intermittent manner. I turned off the compact fluorescent in the living room and everything worked perfectly. I turned on another compact fluorescent in the same room. No problem but once I turned on the original CFL, the IR received LED went "gaga" again.

Anyway, I thought you might be interested since I note that the "Ask Silicon Chip" in the July 2002 issue, the IR on the MP3 Jukebox was causing one of your readers a problem with the programming.

Steve Ballestrin,
via email.

Comment: thanks for the information. The topic of compact fluorescent interference with IR controllers has come up previously in SILICON CHIP but it is worthwhile to repeat the story. We think compact fluoros are diabolical devices anyway.

Digital TV decoder would be a good project There's something that bugs me about paying about $900 for a digital set-top box, particularly when it's in a cheap-and-nasty plastic box and weighs next to nothing! I'd reckon that a project to build one would go like hot cakes in Australia. I was wondering if there are any plans afoot or anything being researched at the moment? James Logan, via email. Comment: that box may be cheap and nasty in appearance but inside it is packed with a heap of LSI chips which cost squillions to develop. We don't think there will be a DIY set-top box anytime soon, if ever.

Extension software for MP3 controller

Over the past few months I have been reading letters regarding the MP3 remote control (see SILICON CHIP, September 2001) in particular, in relation to the Winamp plug-in and what it can and can't achieve. Recently I came across an excellent piece of software which allows the IR controller to control not only Winamp but any other program within the Windows environment, as well as system functions.

Using this software I am now using the project to control Winamp, WinDVD and Windows Media Player, all using the Aifa AV8E universal remote from Altronics. The software is called Girder, is free for personal use and is available at www.girder.nl

In order to use the software with the MP3 controller, the generic serial device plug-in available at this site is required, with the COM port settings to be as prescribed by the original SILICON CHIP article. I also believe that with some driver changes explained on the web site, the PC Infrared Transceiver which featured in the December 2001 issue can also be used with this software, although I have not yet tested this.

Hopefully this information will be useful to you and to other builders of the IR kits.

Michael Green,
via email.

Remote control extender works with Mitsubishi VCRs

I have constructed one of your kits from Jaycar Electronics, the updated Remote Control Extender from the June 1996 issue. It works fine and I was impressed how you included everything I needed.

My issue is that while it worked fine on my NEC television and my spare Philips VCR, it did not seem to be compatible with my Mitsubishi HS-661V (hifi stereo) VCR which is the one I bought the kit for.

Having been informed by you that the project is not compatible with Mitsubishi TVs and VCRs, I persisted. I purchased an AR-1712 (basic 4-in-1 model) learning remote from Jaycar and it now gets through.

The learning remote generates a stronger response on the acknowledge LED than the original remote from the VCR. I am using light speaker wire instead of the figure-8 wire suggested and for adaptability I used an RCA panel-mount socket on the box and mounted the transmit LED inside and protruding from an in-line RCA socket.

I have the transmit LED positioned quite close to the VCR's receive port. More than one way to skin a cat!

Darren,
via email.

Comment: thanks for this tip. Quite a few readers have had this problem.

Fuel cell project would be good I've really enjoyed the series of articles on fuel cells. It is really clarifying an area that I, and I suppose many other people, have had neither the time nor the resources to fully understand. But while I now have some theoretical understanding of the principles, I still don't fully understand how to put it into practice. That is, how to actually make one!? Have you thought of producing a fuel cell project? Say the alkaline fuel cell, seeing that it was the first to be used successfully, is used by NASA and seems to have so many plus points (I'm particularly impressed by the water by-product). I can see such a project being used in schools as well. It doesn't have to be anything elaborate, just to demonstrate basic principles. Jacob Westerhoff, via email.

You can buy products mentioned in this article here : KC5209 : IMPR. REMOTE EXTENDER 7/96 AR1712 : 4IN1 LEARNING REMOTE CONTROL MULTI APPLI