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iksbob's blog
Posted by iksbob | Jul 21, 2012 @ 04:09 AM | 1,753 Views
One minor complaint I've had about the '9x hardware is the clicky trim switches. They're fine for small adjustments, but even with the additional options er9x gives you, it tends to be hit or miss for anything else. You either have to click the switch a dozen times, or hold it down to make it whiz off to who-knows-where.

My plan is to replace the clicky switches with something very similar to a mouse scroll wheel. Panasonic makes a small product line of 'edge drive jog encoders' (rotary encoders - sensors for mechanical rotation) that I'm pretty sure blackberry used in their early handsets. They're about half the diameter of a mouse scroll wheel and maybe 1/3 the thickness, but operate the same way: They spin infinitely in either direction (unlike a potentiometer) yet have detents at regular intervals. Most importantly, these are self-contained components (unlike any mouse scroll wheel I've seen to date) that can be easily purchased (digikey sells them for $5.55 USD each) and installed in a device (at least, when compared to cutting chunks of plastic out of a mouse).

Electrically, the wheel is a pair of switches that turn on and off as the wheel is rotated, following a pattern known as quadrature or 2-bit grey code. The two switches are one step out of sync, which lets you tell which direction the wheel was moved. Since the stock trim toggles already use a pair of switches, the only necessary hardware modifications are to replace the switches themselves. The existing...Continue Reading
Posted by iksbob | Jul 21, 2012 @ 02:52 AM | 1,784 Views
Just noticed this nifty blog thing, so I thought I'd post about my TGY9x hardware mods, and more importantly mods-in-progress.

As of last week I had installed the HK backlight kit (green), soldered in an ISP programming cable, completed the well known piezo speaker mod (replacing the stock beeper) as well as the haptic (installing a cellphone vibrator) mod. The piezo and haptic mods are both installed on the power switch/beeper PCB on the front half of the radio.

The piezo mod differs slightly in that I tried to eke out some additional volume by making it a push-pull setup. The basic design is push-zero, meaning it applies alternating 5V+ and 0V to the piezo element, which comes directly from the radio's processor (ATMEGA). The push-pull setup actually flips the polarity of the voltage fed to the piezo, ideally resulting in alternating +5V and -5V. That doubles the voltage swing and I had hoped the volume. Did it? Not really. It does seem louder, but not as much as I had hoped. A more complex circuit that runs the piezo off battery voltage (rather than regulated 5V) might have better results.

The vibrator motor I used for the haptic mod pulls something like 300mA, so I upgraded the voltage regulator on the switch PCB to handle it. TO-92 package regulators are typically rated up to about 100mA, so I went to a larger TO-220 unit (typically rated at 1A, that's 1000mA for those not up on their SI prefixes).
To make the larger regulator fit, I had to very carefully...Continue Reading