I finally decided it was time to kit out my ancient but trusty Asus Eee 900 with internal Bluetooth. I had an old micro Bluetooth adapter lying about which came apart very easily to reveal an exceptionally small PCB.
I stuck this to the motherboard of the Eee using a small piece of double sided foam tape, just behind the external VGA connector, and then wired it to the unused USB lines connected to the WiFi adapter PCIe slot.
Power was derived from the same 5v rail that supplies the external USB ports. I simply scraped some solder mask off the tracks and soldered the wires directly.
Fortunately once I put it all together again it worked!
I decided to replace the hard disk in my Dell Optiplex 755 with a larger model (500GB). Migrating Ubuntu was trivial; Windows Vista was not. Clonezilla did its best but I ended up running into all sorts of Windows BCD corruption issues. Most of the various repair tools on the Windows DVD failed with incredibly non-descriptive error messages.
After giving up I quickly discovered that Windows would refuse to even install, citing Windows is unable to find a system volume that meets its criteria for installing. This was even after zeroising the first few GB of the disk with dd. WTF Microsoft?
Even a BIOS update didn’t do the trick. (hint to Dell, et al.: DOS is dead. Please give us a modern, OS independent BIOS update mechanism)
It turns out that two things seemed to have an affect on this: my HP Photosmart printer with its built-in card reader and floppy drive setting in the BIOS. Disconnecting the printer and setting the floppy drive mode from USB (default if there is no internal floppy drive) to None cured the problem.
By this stage I had wasted enough hours so didn’t even bother trying to see if the clone would work this time around.
Of course all along Ubuntu behaves just perfectly.
Do you have a Japanese import car that won’t tune to local FM radio stations? It’s a well known fact that Japan uses a different public FM broadcast band to the rest of the world; 76 to 90 MHz instead of the usual 87.5 to 108 MHz CCIR band. Sure you can use a band expander but these suffer from a number of drawbacks, not to mention that the radio does not display the correct frequency of the station you are tuned to.
Here’s a guide on hacking your radio to convert it to natively tune across the CCIR band. This post is still a work in progress so I may update it from time to time and add more photos as I get the chance. Continue reading →
I’ve had quite a few requests for more information about the McIntosh EF-1080I amplifier (often but incorrectly referred to as the EF-10801). This unit is actually made by Clarion and is supplied as stock equipment with many Subaru Legacy and Outback cars manufactured between 1998-2003. Continue reading →
Here’s a quick circuit that allows you to measure the capacitance of a varicap (also known as a varactor).
As varicaps generally have a very small capacitance (typically a few dozen picofarads) it pays to keep the wiring between the varicap (VC) and the capacitance meter as short as possible to reduce stray capacitance.
I recently acquired this lovely McIntosh PF-2510I-A 6-disc in-dash CD changer. This model was available as an option in the North American market Subaru Legacy and Outback. It is often but incorrectly referred to as the PF-25201 or PF-25201-A.
Fortunately it shares the same connectors and pinout as the Japanese and Austrailasian market Legacys so can be fitted in cars destined for other markets with very little effort. Having said that there are a couple of gotchas. Read on… Continue reading →
Stripboard Magic is a Windows application for designing PCB layouts on stripboard (aka prototyping board). It was released by a British company called Ambyr which ceased trading a long time ago. The interface is a quite primitive and a little strange but the program is functional even on Windows XP. It also works great in Linux using Wine. Continue reading →
Here’s a quickie on adjusting the gain of the OEM-suppliedMcIntosh subwoofer in many BE and BH series (MY 1998-2003) Subaru Legacy’s. The subwoofer gain and crossover frequency is non-adjustable, at least until now. : ) If you have such a car and want to get a little more punch from the sub, read on!
The amplifier is bolted to the floor under the drivers seat and has two connectors on the end closest to the door. Disconnect and unbolt the amplifier and take it apart. Make a careful note of where each screw goes as they are not interchangeable; you can permanently damage the amp by shorting things out of you replace the screws incorrectly.
Find R519 on the underside of the PCB near the power and speaker connector. In station wagons this is rated at 10k and in sedans 4.7k, labeled as either 103 or 472 respectively. This resistor sets the negative feedback in the final stage of the subwoofer crossover.
Replace this resistor with a higher value to increase the gain. Don’t leave it out of the circuit or it may overdrive the sub and do damage. If you short it you will mute the sub entirely.
After some experimenting I feel 33k delivers quite a nice bit of punch in a station wagon, which should boost the sub by about 5.2dB. Feel free to choose any value you want between 10-100k. Be careful using high values as it becomes quite easy to inadvertently overdrive the sub.
You might want to use a potentiometer instead so you can adjust the sub gain as you please. If you do this, I suggest a 50k linear (type B) pot in series with a 10k resistor. Make sure you use shielded cable and keep the cable very short to help prevent any instability in the amp. Connect the cable shield to a suitable ground point in the amp and (ideally) a 100nF or similar capacitor between the cable shield and the pot casing to prevent possible ground loops.
Here’s an example on multiplexing three seven-segment LED displays from an Arduino using a single 4511 IC and a handful of transistors. This builds on my last post about interfacing to a single display