Monthly Archives: April 2017

Wipe and wait

My car has a 4-position windshield wiper stalk; off, intermittent, slow, fast.

While the motor needs to be pulled and serviced because there’s little difference between slow and fast, the intermittent wipe had always been somewhat pathetic.

Selecting intermittent would make the relay click, and as soon as the wipers returned to the parked position, click again and they would almost immediately wipe again.

Pulled the dash shroud down and located the clicking box at the top left. (Top right is the key-in/seatbelt buzzer, bottom left the cruise control stalk, above that with the finned heat sink the dashboard dimmer control).

relay delay box

Took the circuit board out and drew up the circuit diagram by following the traces, to get a better understanding of the circuit and its method of operation.

board

Culprits were most likely the electrolytic capacitors. One had a high ESD and the other was meant to be 22uF, it measured in at about 100nF. Replaced them both. Now the wipers wipe and wait about 5 seconds before wiping again on intermittent, and added bonus, they now wipe 3 times after spraying screenwash onto the screen. Not bad for 45 minutes’ work and spares I had in stock.

Odds and ends

Been busy with Scouts events lately. First off was the Raingutter Regatta, which is an event where you build a boat from a kit and then race against other people with boats by blowing at the sail through a drinking straw.

Didn’t win any races but the boats were decorated that morning with Sharpie permanent markers. We have the Cheshire Cat from the latest edition of the Alice In Wonderland films, and Edvard Munch’s “The Scream”.

boats

That was a bit of fun. Next up was the Space Derby, which is basically elastic-band, propeller driven craft that fly along a zipline. Furthest wins, or first to the end of the run, which is about 30 feet or so of fishing line, held taut.

airplane

We went for a heavier design which won it first place in the races (not the fastest but it managed to gain the most momentum and coasted on by faster but shorter-traveled competitors). Designed after the P52 Mustang.

wheel off again

Took the wheels off the front of the car again, and changed the brake pads for new ones. The brakes had good pedal but offered little actual braking effort.

glazed

The pads were so glazed I could almost see my face. Plenty of friction material but all cracked up. In the bin they went. The brakes now work properly. That’s better.

Co-processing.

I decided to buy a little something for myself, so eBay was opened up and I hit “Buy It Now” on an item.

Package

3 weeks later, it arrived from Kowloon, Hong Kong. The reason for the package? This empty socket.

socket

As if by magic, it was filled with a suitable device:

387

Upon fitting a 387 co-processor, a jumper needed to be shorted to inform the board to use it.

jumper

CheckIt determined that the thing was working (which is good, as there are surprisingly quite a lot of fake/broken chips circulating the market).

checkit

It was then tidied up into the desk. Makes a significant improvement where a math co-processor is utilized.

lotus 3

A bit of fun, reminder of days gone by.

Some new subjects to focus on

As mentioned in an earlier post, I recently acquired a Canon A-1 35mm film camera. It dates to 1978, and it was Canon’s first foray into fully automatic exposure cameras.

It gives a digital readout of the f-stop (aperture) and exposure time through the viewfinder using red LED numerals (which can be disabled), you can hold the reading for backlit scenes, calculate both, just the aperture or just the exposure time. Very innovative for the day, just focus and click. I got the pictures back that I had taken from being processed. Here’s a small selection:

Bayou Lafourche at Leeville
Bayou Lafourche at Leeville.

Hydrant
Experimenting with depth of field.

Leeville North, LA Hwy 1
Louisiana Highway One, at North Leeville. Once the busiest road in the area, now a ghost town.

Captain Thuan
Fishing boat, Bayou Lafourche, Larose.

It does have a light leak on the right hand side of the mirror. After a little reading, it seems that’s fairly common on these as the felt stripping that blocks the light disintegrates with time.

Pointe des Chenes

Compare with a modern digital image, adjusted with a warming filter. Quite different. I like both, but all the images taken with the Canon look like they could easily have been shot in 1985.