I’m currently attempting to get a batch of RS232 Rate Converters made in China, I’ve been getting the PCBs etched in China for months now so this is the logical next step.
The biggest problem so far has been sourcing the parts. I’m getting most of the stuff from DigiKey because they specialize in smaller orders – I don’t have the sales volume to justify making 1000 of these things.
But get this. DigiKey will not deliver microprocessors to China, because of export restrictions, for a microprocessor that was made in China in the first place!
Ah well, I found a Chinese supplier for the microprocessors thanks to the very excellent alibaba.com so I have all the parts on their way now.
So stay tuned, I’ll post photos when I get the assembled boards back from China.

If you scroll down and look on the left you’ll see a new climate-change widget I got from wattsupwiththat.com (yes I know they’re a bunch of climate sceptics but their widget is good). I don’t normally put such junk on my website but this one will remind me every day of the need to work towards solving the problems of the planet.

The Serial Bit Rate Converter runs an ARM7 CPU which is complete overkill for the simple job of relaying serial data. I’ve often thought I should redesign it to run a cheaper and less powerful CPU like a PIC or AVR. I originally designed it with an ARM7 simply because I like them and enjoy programming them.

Another reason I never redesigned it for AVR is that the economics are not that great. It would probably take $5 off the price but cost me a couple of weeks of time to redesign the entire thing.

This decision has had an unexpected benefit recently. A customer asked me if I could add an extra function to search-and-replace byte sequences in the data stream. Now I’m really glad to have 50 MIPS on board because a smaller CPU might not have had the grunt to do the job.

So having a way-too-powerful CPU has produced a long-term benefit to enable me to quickly sieze a market opportunity.

I haven’t written very much about my goals here. My general long-term goal is to produce a range of for-sale products which might be either hardware, software or a combination of both, but my short-term goal is to simply become faster at designing and implementing stuff and that means:

1. Being able to learn new technologies quickly
2. Picking and choosing which design techniques to use to make a good match with my experience and strengths
3. Remaining focused and managing my time well

I was quite pleased to get the Volume Box product from concept to production in only six weeks – especially since most of that time was spent waiting for suppliers and subcontractors, I probably only spent 10 days of my own time on it.

But of course I’ll have to try to be even quicker next time.

I already know what my next product will be but I am up to my eyeballs in contract work at the moment which, while it does pay the bills, takes up all my available time. So I will have to hold off until I get the contract jobs out of the way, then I can go hard on the next product and see how quick I can do it.

Finally I have all the parts and I spent last night assembling ten boxes to fill my first order. It looks not half bad.

Next I need to set up a web page and finalize pricing so anyone can buy one.

So what is a Volume Box I hear you ask? Well, the Volume Box is a digital stereo volume control. It has no knobs or buttons, it is controlled via serial commands from a PC or home automation system. It is intended to be used as a component in an automated audiovisual setup such as conference centres, classrooms etc.

Features include:

• Attenuation from 0 to -95dB in 1dB steps
• 3 way stereo input selector
• Line level inputs and outputs
• Optional 7 watt power amplifier
• Mute function
• Preset store and recall

I’m getting orders for the Volume Box already. I haven’t even put up a web page for it. But wouldn’t you know it, the plastic case I want is not in stock with any of my regular suppliers (at least, those ones who are not still on extended Christmas holiday) so I’m having to get some cases flown in from England of all places so I can fill the orders. Of course I am going to have to absorb the extra cost of that, I wonder if Sony ever has these kind of supply-chain problems.

The Volume Box board is assembled and tested, the last few firmware bugs are squished and the only thing missing now is the machined end panel for the plastic case and it is ready to sell!

Here are the lessons I have learned:

1. PICs can be a mighty pain in the bum to debug, particularly the peripherals. I think I’ll use a different chip next time.

2. Always check your component footprints when designing a PCB, the Protel footprint libraries are full of errors. I’ll be patching the first run of boards due to a bad footprint.

3. Don’t try to get a product out the door around Christmas time, many manufacturing companies are closed for the holidays especially here in Australia where we combine our summer holiday and Christmas holiday into one big long holiday. Some companies do not resume business until January 18th!

Anyway, now the design is proven I have ordered some parts to begin producing these things.

I’ve finally taken delivery of my first batch of printed circuit boards for the Volume Box. They look real nice. As usual I got them from Gold Phoenix of Shanghai – The quality of the boards is pretty good and their prices are good for very small runs.

My chips and other parts have already arrived so next I need to assemble it and test. I’ve still got a lot of tasks after that before it is a finished product such as designing the end panels of the box, writing the user manual and setting up a website for it.

Phew, my parts have finally arrived so I can start taking orders again for the RS232 Rate Converter. I was really stressed over the last week about having no stock but now I can breathe easy again.

Sales of the RS232 Rate Converter were a little slow throughout October and November but they sure have caught up in the last couple of weeks. I thought I had enough stock to see me through until January but after a flurry of orders, I am now completely sold out.

So I’ve been frantically ordering parts to build more units ASAP. I suppose having too many orders is a good problem to have, better than having no orders.

I’ve no idea why sales have suddenly surged, it’s not the kind of thing you’d buy as a Christmas present!