Sunday 20 December 2020

A new tow vehicle for Elena

My old pug that used to tow Elena became very unreliable, with crankshaft position sensor errors and other sundry issues cropping up regularly. Its age was such that we were going to have to do timing belt and particulate filter, and there was a fair bit of panel damage from an intimate encounter with a roo. So when rego came due last year we took it to the wreckers.

Since then we haven't had a car with a towbar.

I've been talking about getting a ute for ages, and recently my main car has been off the road (another roo), so we brought that forward. Top of the list was something that could comfortably tow Elena. I also wanted something that would be good for picking up piles of wood for the next boat. I decided something with a tray 2.4m long would be perfect, as so much wood comes in 2.4m lengths. Also I didn't want to spend too much, as it's a second car and will have it's arse dipped in the water occasionally.

So meet our new ute. It's a bottom of the range Mitsubishi Triton single cab, with a tray. It's a 2011 model, with 120,000km and is as simple as a vehicle can be. And it's just the ticket for towing Elena.

I've come up with a simple method of securing the mast so it doesn't scuff the floor, just by hanging it between the aft mooring cleats. I'll sew bags for the rest of the bits.

Tuesday 8 December 2020

AEM6000 Based 50W and 100W Amps

This is a design I've had in use for rather a long time. It started life as a design exercise to see if I could do a more space-efficient board for my original AEM6000 based amps, as I wanted something that would fit on a 50mm high heatsink. Along the way it changed a little from Tilbrook's original in topology, and rather a lot in component choice. It has better performance than my original design, both through a better tighter layout and also through the use of faster transistors.

I've built a bunch of these, using both Renesas and Exicon lateral MOSFETs, and subjected them to all manner of abuse. I had one fail, due to a leaky mica compensation capacitor (see noiseUnit speaker thread), but apart from that they've been rock-solid.

Lots of component substitution is reasonable. I like to use MELF resistors, but that's mostly just bloody-mindedness. An exception is the feedback divider. No, It won't work with cheap vertical MOSFETs.

The design is free for use for non-commercial purposes.

The 50W design is available on my Google drive

The 100W design is available on my Google drive