Thursday, October 4, 2012

Calibrating a Cheap Digital Thermometer

et's say you're relaxing some evening, enjoying a few homebrews, and shopping eBay. With some beer logic, you click BuyNow on a digital thermometer for $1.83 (free shipping!) from a seller named Hola-Fly in China. Let's say, you forgot you ordered it and eight weeks later it surprises you in the mail ...but to no surprise it's not very accurate.

Okay, let's say I did this.

My plan was to install it in my beer fridge so I could keep an eye on my beer temp. If Coors Light drinkers can have their "certified cold" mountains, I should at least have a thermometer. Unfortunately this cheap little thermometer measured about 4°C too warm. And of course, since it costs less than a large coffee, there is no setting to calibrate it.

The probe is likely a simple thermocouple but could be a resistance thermometer - either way it's effectively a variable resistor affected by temperature. I figured I might be able to increase the resistance to get the results I needed.

I cut the lead and spliced in a 5KΩ trimpot (trimmer potentiometer) to one of the wires and dropped it in the fridge along with another thermometer that I trust. Waiting 10-15 seconds after each adjustment, I tweaked the trimpot until I was consistently getting the correct reading. With the trimpot removed, I measured it to be set to 2.2KΩ. I didn't have a 2.2KΩ resistor ( ▌▌▌) so I used a 1.2KΩ ( ▌▌) and 1KΩ ( ) in series. A little soldering and heat shrink and it's all good.

I should point out, this isn't really "calibrating". I just increased the resistance across the entire range - I'm betting it's not a linear relationship between the temperature and the resistance. However, it's now pretty accurate in the 0°C - 10°C range (above 10°C it starts to deviate). Good enough for a beer fridge.

Friday, August 17, 2012

1959 VW Ad - Gerhard Baecker teaches Volkswagen

Gerhard Baecker teaches Volkswagen
(Or why Volkswagen service is as good as the car)

Gerhard Baecker, schooled in Wolfsburg, Germany, now teaches Volkswagen in the United States. Like most teachers, Gerhard be-lieves in what he teaches. He shares whole-heartedly the Volkswagen philosophy: the car is only as good as the service it gets.

As a result, you'll find Volkswagens are serv-

iced only by graduate mechanics trained to demanding Volkswagen standards.

Volkswagen service is fast. Your Volkswagen engine can be removed and replaced in 90 minutes. A fuel pump installed in 20.

Every authorized Volkswagen dealer has a complete inventory of VW parts on hand.

There's no wait, no substitution.

Volkswagen parts are inexpensive. A new front fender is $21.75,* a cylinder head $19.95.*

If you've been thinking about buying the Volkswagen, isn't it nice to know the service is as good as the car?

Wednesday, August 15, 2012

1962 VW Ad - The Volkswagen Theory of Evolution.

The Volkswagen Theory of Evolution.

Can you spot the Volkswagen with the fins? Or the one that's bigger? Or smaller? Or the one with the fancy chrome work?

You can't?

The reason you can't see any revolu-tionary design changes on our cars is simple: there aren't any.

Now, can you spot the Volkswagen with

the synchromesh first gear? Or the one with the more efficient heater? How about the one with the anti-sway bar? Or the more powerful engine?

You can't?

The reason you can't see most of our evolutionary changes is because we've made them deep down inside the car.

And that's our theory: never change the VW for the sake of change, only to make it better.

That's what keeps our car ahead of its time. And never out of style.

Even if you aren't driving the most evolved VW of all.

Our '63.

Thursday, August 2, 2012

1961 VW Ad - No point showing the '62 Volkswagen. It still looks the same.

No point showing the '62 Volkswagen. It still looks the same.

No heads will turn when you drive a '62 Volkswagen home.

(Maybe an eagle-eyed neighbor will notice that we've made the tail lights a little bigger. But that's the only clue.)

Everything is right where we left it in '61. Including the price: $1,595.*

Inside is another story.

We've put all our time and effort into

improvements that matter.

The '62 VW runs more quietly. There are new clutch and brake cables (as well as new steering parts) that never need maintenance. Heater outlets front and rear for more even heating. Easier braking.

And 24 more.

One change is literally a gasser.

We've added a gas gauge. Our first.

A few die-hards may think we've stolen some of the VW's sporting flavor. But the gas gauge may be more useful than you'd imagine. It will not only tell you whether your tank is E or F; it will prove you're driving a '62.

It could make 1962 go down in VW history as the year of the big change.

1956 VW Ad - Why the engine in the back?

Why the engine in the back?

In conventional cars, a front engine turns the rear wheels through a long drive shaft.

But Volkswagen's rear engine gives direct power to the wheels, saving weight and power. It is the most efficient and eco-nomical design. It means greater visibility when driving - you see over VW's snub nose. And the rear engine gives your rear wheels better traction.  In mud, sand, ice,

snow, where other cars skid, you go.

Its location, however, is the least un-usual feature of a Volkswagen engine. For one thing, it is air-cooled, an astonish-ing advantage when you think about it. No water to boil over in the summer, or to freeze in winter. No anti-freeze needed. No radi-ator problems.

The engine is ingeniously cast of alu-minum and magnesium alloys and is very

light and powerful; undoubtedly the toughest 198 lbs. going.

It is beautifully machined for minimum friction; you will probably never need oil between changes. And so efficient that top and cruising speeds are the same.

Your VW runs at 70 mph all day without strain. You get an honest 32 miles to the gallon (regular gas-regular driving).

1966 VW Ad - Don't let the low price scare you off

Don't let the low price scare you off.


That's the price of a new Volkswagen.

But some people won't buy one. They feel they deserve something costlier. That's the price we pay for the price we charge.

And some people are afraid to buy one. They don't see how we can turn out a cheap car without having it turn out cheap.

This is how.

Since the factory doesn't change the

bug's shape every year, we don't have to change the factory every year.

What we don't spend on looks, we spend on improvements to make more people buy the car.

Mass production cuts costs. And VWs have been produced in a greater mass (over 10 million to date) than any car model in history.

Our air-cooled rear engine cuts costs

too, by eliminating the need for a radiator, water pump, and drive shaft.

There are no fancy gadgets run by push buttons.

(The only push buttons are on the doors. And those gadgets are run by you.)

When you buy a VW, you get what you pay for. What you don't get is frills. And you don't pay for what you don't get.


Wednesday, August 1, 2012

1969 VW Ad - Live below your means

Live below your means.

If you'd like to get around the high cost of living, we have a suggestion:

Cut down on the high cost of getting around.

And buy a Volkswagen. It's only $1799*.

That's around $1200 less than the aver-age amount paid for a new car today. (Leave it in the bank. More's coming.)

A VW saves you hundreds of dollars on upkeep over the years.

It takes pints, not quarts, of oil.

Not one iota of antifreeze.

And it gets about 27 miles to the gallon. The average car (thirsty devil that it is) only gets 14.

So the more you drive, the more you save.

And chances are, you'll drive it for years and years. (Since we never change the style, a VW never goes out of style.)

Of course, a VW's not much to look at. So a lot of people buy a big flashy car just to save face.

Try putting that in the bank.


Tuesday, July 24, 2012

Faulty Ignition Switch

1 911.613.011.06 Ignition switch, mechanical portion
1/1 911.613.125.00 Buzzer contact
2 911.613.017.00 Ignition switch, electrical portion
3 - Key
4 911.347.359.01 Reinforcement plate
5 999.219.017.02 Shear bolt (x2)
6 911.613.169.00 Washer
7 911.613.160.00 Rosette
ike most vintage Porsche owners, I found myself dealing with a faulty ignition switch. For the last year or so, intermittently it had not been working, then intermittently it worked, and finally it became a bit of a lottery. All key positions were functioning except the last click - engine start.

After reading about the common failure of the electrical portion of the ignition switch (#2 in diagram), I overnighted a replacement. Grabbing my favourite Porsche DIY book - Wayne R. Dempsey's 101 Projects for Your Porsche 911 - I flipped to page 212, Project 91 - Replacing Your Ignition Switch (Google Books and Pelican Parts have some of it online - but you really should buy the book!)

My first challenge was to remove the two shear bolts (#5 in diagram). A shear bolt is a type of security fastener with a head that breaks away after tightening to prevent easy/criminal removal. After some careful drilling and using a Mastercraft GraBit I managed to back out the bolts without needing to remove the steering wheel.

Removing the shear bolts

With a glowing sense of accomplishment I installed the new switch... and had the same problem.

With a now deflated sense of accomplishment, I deciding it would be wise to actually diagnose the problem. First I checked all ground straps and battery terminals. Then I decided to test for power at the solenoid. The main line showed a strong 12.4V but the other two wires were flat when the key was turned to the start position - so I knew it likely wasn't my starter/solenoid.

I then tested the electrical portion of the ignition switch separate from the mechanical portion (what I should have done to begin with) by turning it with a Phillips screwdriver... Eureka! the engine roared to life. I now knew it was the mechanical portion (#1 in diagram) that was faulty.

Looking closely at it, I noticed it wasn't turning quite far enough, maybe 15° short of the full start position.

After several days of driving with the electrical switch swinging by my knees and a Phillips stubby in the ash tray, I figured I either need to dish out the $600-700 for a new ignition switch or try to repair the one I had. If I were to buy a new one I'd need to open it up to rekey it, so I decided to disassemble the old one as practice with hopes of maybe finding an easy fix.

To release the key barrel/tumbler, I used a 1/64" bit to drill out the single pin. With the barrel out I could see it was showing some age and was a bit sloppy.

At the tail-end of the tumbler there are two plates that turn with the key - the thicker outer one turns with the key and the thinner, inner one turns a bit out of sequence. Mine were turning at the same time.

In a functioning mechanism, when turned clockwise, a spring-loaded pin clicks into a hole and turns the inner plate. Then when turned counterclockwise, the pin pops into a notch on the outer disk, preventing it from being turned clockwise again until turned all the way back. This "start lockout" prevents the car from being restarted after it's already been started.

Without taking the tumbler apart, I tightened things up significantly by hitting the two pins at the back with a hammer and punch.

To save the next guy (or future me) some trouble, I tapped the pin hole and replaced the pin with a cone point set screw. Also, when installing the ignition back in the car I used regular bolts instead of the OEM shear bolts.

Here are two posts on the Pelican Parts Technical BBS dealing with the same problem:

Wednesday, May 16, 2012

Autostick Electrical Diagrams II

Here are a few more autostick electrical diagrams.

Schematic of pre-1972 electrical circuit of the Automatic Stick Shift

© 1972 VWoA

Schematic of the electrical circuit for the Automatic Stick Shift on 1972 and later models

© 1972 VWoA

Autostick Electrical Diagrams

Here are a bunch of autostick electrical diagrams.

Automatic Stick Shift and Rear Window Defogger Circuit for VW Type 1/Sedan 113 — from August 1969 (1970 and 1971 Models)

Automatic Stick Shift, Rear Window Defogger Circuit, and Fresh Air Fan Circuit for VW Type 1/Sedan 113 — from August 1970 (1971 Models)

Automatic Stick Shift Circuit for VW Type 1/Sedan 111 and 113 — from August 1971 (1972 Models)

Tuesday, May 15, 2012

Autostick Oil Pump and Control Valve

Here are a couple handy diagrams from Volkswagen of America.

Dual pump for Automatic Stick Shift

© 1974 VWoA

Control valve for Automatic Stick Shift

© 1972 VWoA