Well, Silver Circuits manufactured and delivered my PCB much much quicker than expected and I'm not complaining!
And, last night, after a rush of construction... I couldn't get the board to work... The 'trip' sensors were permanently active! After a 30 minute stare at the circuit design today I'd realised I'd viewed an older circuit schematic when designing the PCB and had put the inputs to the LM339 the wrong way around!
After a quick test to correct this I had the booster operational.
Unfortunately this now means that all boards in this initial run are defective, but I have devised a way to correct the issue without too much hacking. A small veroboard piggy-backed on has allowed me to correct the inputs to the IC.
I was very much relieved once it was all operational. I now need to get the final components (you can see a dodgy-hack of resistors wired on) and the heatsinks in place.
Then I'll find a neater box to mount it all in and all should be set to go.
Well, after a long fight of finding appropriate software and then design I've finally sent off the final (if not entirely messy) design to the manufacturers...
Sure, it's not as small as I would have liked... but it's all set in stone now. I should see 8pcs on my doorstep in around a fortnight and then I can finally produce a finished product.
I can't wait actually... Last weekend I tested the final prototype on my own layout... which really only allows for around 3 trains running (one on a branch, one stuck in a siding and one on the main) and my battery ran out on the laptop before I had a chance to fully test it all out... either way, the quick test ran perfectly on all accounts:
I also purchased two DCC Accessory Decoders from eBay. I coded those in to trainControl (you'll see a few little squares above the console messages and below the train throttles) and they work great. Unfortunately they cannot be wired directly to the Kato UniTrack points (you'll need to wire a few relays in between) but I'm told work well on the Peco points. I didn't get to test them at the time.
The DCC Accessory Decoders did require me to do a bit of fine tuning on the Booster circuit though; it turns out they suck quite a bit of current on power-up to charge their little capacitors. This meant that the initial current draw on the booster was exceeding the trip circuit and the whole system would not power on.
After a little help the 1K2 resistor providing the op-amp comparison voltage was incremented to a 1K4 and everything worked fine.
This made me realise that the circuit will have different requirements for different layouts and so the final design will now incorporate a trimpot (initially set to 1K4) that can be user adjustable [but WILL void warranty] for 'expert users' to adjust.
Anyway... the work continues... everything is now set. I'm quite proud of the entire system and I can't wait to see the final circuit boards!
UPDATE: The boards are already done and on their way (priority) to me... thanks to Silver Circuits!
Ok, hot off the development 'floor':
...is the Booster Prototype 2.
This now includes short-circuit protection! The final design will have 2 outputs (for two separate segments of track) at 3Amp each (depending on power supply capabilities.)
There are now 4 status LEDs (Supply Power, Data, Overload, Track Power/Data)
More to come as I finalise the circuit board design.
[PHOTO OF Kirara 900] I'd bought both the Maple Red and Maple Orange versions of this EMU back in 2006 when I first went to Japan and have always loved the quality and performance.
Since the latest trend has been to DCC all my gear, I had decided that what better candidate next than to do one of these up. It was all quite simple too. The 'power rails' run down each side (internally) of the chassis and after isolating these from the engine I soldered the decoder in.
Firstly I took the thing to bits... I love Kato and their use of clips... everything snaps apart, but you really need to be careful! I nearly broke one clip underneath as you have to squeeze them with a fair bit of force.
After disembowing the engine I soldered it directly to the Decoder as I could easily put it back without having to worry about where the wires ran.
Putting it back in was easy and the next step was to wire up the main power to the copper rails.
There's a pair of LEDs (Red/Orange) at either end and they're wired up in parallel where one is reversed to allow them to switch between reverse/forward marker lights.
This of course, wont work with DCC as you now have one common (single polarity) wire and then two rev/fwd wires... so I ripped one LED out of the board, flipped it around and then had my common.
I then used some very fine-gauge 'winding wire' (used for transformers/magnets) to connect the LEDs up (there was already a resistor in the circuit) since the thicker decoder wiring wouldn't fit under the light shield.
To get the lights in the rear trailer working I ran this wire all the way between the trailers and to the other board, resoldering it in the same way.
I also ran an extra two wires from the 'power rails' in the trailer to the rails in the motor car. Therefore ALL 4 bogies were wired for power pickup and the thing ran like a dream (initially it was a bit sloppy with only the 2 power car bogies picking up the power.)
After programming it to use address 12, it was set to go.
Next is to do my Maple Orange.
...actually, I'll get back to the programming first... I want to have my app able to at least set the addresses on decoders.
After a few more days of work the trainControl application has evolved further:
- Loading and saving of trains/connection config
- Add/Delete trains via interface
- Connect/Disconnect on the fly
Still more to go... but very functional now...
Download the source here.
Be warned! ... The source is constantly being updated by me and may DESTROY your computer.
I've also considered the next challenge on this project... Handheld control via a GamePark GP2x.