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)

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

From a Poster to the Real Thing

I

n 1984, at the ripe age of ten, I was immersed and infatuated by the blitz of mid-eighties sports cars being imported to North America. Like every kid, I had the Hot Wheels, the magazines and the posters. In fact, an entire wall of my bedroom was dedicated to car posters. It started with just any "cool car" - but it quickly became exclusive to Porsches. I specifically remember receiving two posters as birthday gifts, a red Testarossa and a white Countach. Both were soon demoted to a lesser wall and eventually rolled up and ungratefully jammed in a closet - unworthy of my Porsche shrine.

I collected posters of all colours and all models: Targas, Carreras, SCs, RSs, 924s, 944s, 928s... but the center of my attention was the voluptuous 911 Turbo (or, as I'd remind everyone, "not just a 911, it’s a nine thirty"). This car, in my preteen mind, had everything in the right place. It was the perfect balance of what a sports car should be: friendly but mean, subtle but aggressive, both Bruce Wayne and Batman. Even a few years later when I was taken aback by the revolutionary 959 (this exact poster), I remained true to my first crush.

Road&Track January 1986 The January 1986 issue of Road&Track cemented it for me. On the cover was a line-up of four guards red Porsches led by the one-and-only, the almighty, 930. I can't tell you how many times I read that article. Whenever the Turbo was mentioned, I would intentionally slow my reading and savour the words.

Growing up in rural Nova Scotia I didn't get to see too many exotic cars in the flesh. However, every few months the family would pile into the station wagon and take the hour-and-a-half drive to "the city". This excursion always became a bit of a hunting trip for me. I'd scan the hundreds of cars whizzing by, waiting for a glimpse of a Porsche...just hoping to see an allusive 930. On the rare occasion I'd get a glimpse of one and would instantly become fixated. I wouldn't be able to pull my eyes away. My dad would joke, "Don't stare son! Maybe that's all the poor fella can afford."

As I neared the age of sixteen, I had the inevitable and disheartening realization that my first car would not resemble any of my posters. So I did some homework and learned that Volkswagens were a not-too-distant relative of the Porsche. With a non-existent budget, I found myself in a ten-year-old hand-me-down grey 1980 VW Rabbit Diesel... <sigh>.

Now fast forward about twenty years and several Volkswagens later. In the Appalachians of Pennsylvania, on a winding mountain road cut through a stand of old-growth ash trees, I find myself behind the wheel of a black 1984 930. The cool fall air slipping over the car, down through the huge intercooler and getting sucked into the hungry 3.3 litre. Half excited and half frightened by the savage snarl behind me, I glance at the tach, depress the heavy clutch and reach for another gear.

Later that day I traded my hard-earned savings for the keys.

That day... Obviously when a lifelong dream is suddenly staring back at you, there is a certain degree of surrealism. Amidst the euphoric haze, my most overwhelming impression was that is was nothing like what I'd dreamt it would be. But of course how could it live up to the immortal superhero conjured up in my ten-year-old imagination - after all, it was just a car. No power steering, no power brakes, big turbo lag, unwieldy in the rear... Don't get me wrong, it was in no way disappointing. It was what it was - and it was real!

In Atlantic Canada we store our collector cars through the winter months, keeping them from the perils of snow and road salt. Surprisingly in some ways this is kinda nice. Watching the snow melt, the anticipation of that first spring drive becomes so climactic. Yesterday was that day once again. As the seat bolsters hugged my sides, I felt the direct steering, the turbo lag - the smells, sounds and textures were all the same ...I got that same involuntary grin on my face and I relived that first drive all over again.

Specific Gravity and Brix/Plato Conversion

If you are buying a new refractometer for brewing purposes, look for one that includes the SG scale (ideally both SG and Brix/Plato) - then you can skip all this conversion nonsense.

I

'm sure a lot of homebrewers face this - you get a new refractometer (which usually measures in degrees Brix or Plato) however almost all homebrewing documentation refers to Specific Gravity (SG). So you go looking for a conversion formula - I mean, how hard could it be? When searching you will find a mix of information: a general "rule of thumb" (see below), a few online calculators (that produce varying results) and a bunch of reference tables - all are workable but the inconsistencies are somewhat disconcerting. I'm the kind of guy that needs to know why things are the way they are, so this blog entry is a summary of what I've found.

Specific Gravity

First some background. Specific gravity, or more correctly, relative density, is the ratio of the density of a liquid to the density of pure water.

SG	= DS : DW
	= DS/DW

Where,

• D_S is the density of the sample liquid,
• D_W is the density of pure water, and
• SG is the specific gravity.

So, of interest to brewers, when there is more sugar dissolved in a liquid, like unfermented wort, that ratio is greater than after fermentation. The most common tool used by homebrewers to measure the relative density of a liquid is a hydrometer (or more properly called a saccharometer).

Temperature Correction

When measuring SG with a hydrometer you should be aware of the temperature of the liquid - especially when dealing with hot wort. Warmer liquid is less dense so the SG will read lower than it would when brought down to room temperature. This is important since hydrometers are calibrated for a specific temperature. The following is a formula for the SG temperature correction for hydrometers calibrated at 15°C (59°F):

SG'

=

SG + 1/1000(-2.627634×10-6Ts3 + 2.057793×10-3Ts2 - 1.32674×10-1Ts + 1.313454)

Where,

• SG is the measured specific gravity
• T_s is the temperature of the sample in degrees Fahrenheit (°F), and
• SG' is the corrected specific gravity for a hydrometer calibrated at 59°F.

And of course:

TF = 9/5TC + 32

⇔

TC = 5/9(TF - 32)

Where,

• T_F is the temperature in degrees Fahrenheit (°F), and
• T_C is the temperature in degrees Celsius (°C).

For example, if we have a 40°C (104°F) sample measuring 1.028 in the hydrometer, the formula above tells us that we need to add 0.0068, resulting in a SG of 1.035 - a significant difference.

But not all hydrometers are calibrated for 15°C. So here is a formula for the SG temperature correction for a given hydrometer calibration:

SG' = SG(	2.32820948×10-9Ts3 + 2.04052596×10-6Ts2 - 1.34722124×10-4Ts + 1.00130346	)
	2.32820948×10-9Tc3 + 2.04052596×10-6Tc2 - 1.34722124×10-4Tc + 1.00130346

Where,

• SG is the measured specific gravity
• T_s is the temperature of the sample in degrees Fahrenheit (°F),
• T_c is the calibration temperature of the hydrometer in degrees Fahrenheit (°F), and
• SG' is the corrected specific gravity.

Brewer's Points

Brewers often use a shorthand unit to describe specific gravity called "brewer's points" or just "points". We drop the 1 and multiple by one thousand (moving the decimal point up three spots). For example, an SG of 1.035 is sometimes referred to as 35 points; e.g. 1.035. So mathematically:

BP	= 1000(SG - 1)

Where,

• SG is the specific gravity, and
• BP is the brewer's points.

Refractometers

So why use a refractometer? First of all, refractometers are great because you only need a few drops of sample liquid which reduces waste and risk of contamination. Also, most refractometers have an Automatic Temperature Compensation (ATC) so no correction needed. However, a refractometer actually measures the index of refraction of the liquid, not the specific gravity. The good news is that the index of refraction of a liquid is directly related to its density (affected by, for example, the amount of sugar in the liquid), which in turn can be used to calculate its specific gravity.

Brix / Plato

The units often used to indicate the amount of sucrose in a liquid are degrees Brix (°Bx) or degrees Plato (°P). There's lots of history as to how these scales were developed and evolved; e.g. the Brix scale is based on the Balling scale (other scales include Baumé and Oechsle). For most purposes, Brix and Plato are interchangeable; e.g. 9.99325°Bx = 9.99359°P. Traditionally brewers use the Plato scale and vintners use the Brix scale. These scales correspond to the percent of sucrose in a pure water solution (by weight). So if we have a 1kg solution that we know contains 90g of sugar (i.e. 910g of water), we would have 9% sugar by weight, that is 9°P, or equivalently 9°Bx.

UPDATE: Most refractometers have been designed for measuring sucrose solutions; unfortunately maltose has a slightly different refractive index (and wort contains some other non-sugar bits that alter the solution's refraction). Every brew is a bit different so one way to estimate the difference is to compare your refractometer with a hydrometer for that particular solution. Typically the refractometer will be somewhere around +2 to +6%. Having to use a hydrometer every time kinda defeats the convenience of a refractometer so most people simply adjust their Brix measurement by 4%.

Bx'  ≈

Bx 100% + 4%

=

Bx 1.04

Where,

• Bx is the measured degrees Brix (°Bx) of a maltose solution measured using a sucrose refractometer, and
• Bx' is the adjusted degrees Brix (°Bx).

Conversion Formulas

The relationship between SG and the Brix/Plato scales is not linear, it's close but not quite. Several formulas can be used to approximate this curve. For the Plato scale, here are three functions, from the least accurate to the most accurate: a linear equation (Rule of thumb), a quadratic (Lincoln) and a third-order polynomial (Cubic).

PRule of thumb =	1000(SG - 1)
	4
=	BP 4

Where,

• SG is the specific gravity,
• BP is the brewer's points, and
• P_{Rule of thumb} is the degrees Plato (°P) calculated using the "Rule of thumb" formula.

PLincoln =	(-205SG + 463)(SG - 1)
=	-205SG2 + 668SG - 463

Where,

• SG is the specific gravity, and
• P_Lincoln is the degrees Plato (°P) calculated using the Lincoln quadratic formula.

PCubic =	135997/1000SG3 - 63034/125SG2 + 11117/50SG - 616217/250
=	135.997SG3 - 630.272SG2 + 1111.14SG - 616.868

Where,

• SG is the specific gravity, and
• P_Cubic is the degrees Plato (°P) calculated using the cubic formula.

UPDATE: Here is yet another conversion formula associated with the Plato scale:

PCubic2 =

190.74SG3 - 800.47SG2 + 1286.4SG - 676.67

Where,

• SG is the specific gravity, and
• P_Cubic2 is the degrees Plato (°P) calculated using another cubic formula.

Here is a conversion formula associated with the Brix scale.

Bx = 2613/10 ( 1 -  1 ) SG

⇔

SG =  1 1 -  Bx 2613/10

Where,

• SG is the specific gravity, and
• Bx is the degrees Brix (°Bx).

Conversion formula comparison As you can see, the Plato "Rule of thumb" formula is the easiest to remember and is within one SG point up to 15°P. However if you are brewing imperials or other high-gravity beers, you are better off using one of the other formulas (which are all pretty close).

This brings us full circle to the reference tables. Rather than take the time to run the formula, a lookup table is quite handy (although it's good to know which formula the table is based on). Here (TODO) is one that I made and keep with my refractometer. I also use a clear sheet protector to save it from any inadvertent mash splash.

Calculators

Here are two calculators that use the formulas described above:

Brix ⇒ Specific Gravity
Brix (using a sucrose refractomer):	°Bx ()
Adjustment (for a maltose solution):	% ()
Specific gravity (SG):	⇔   points

Specific Gravity ⇒ Brix and Plato
Specific gravity (SG):	⇔   points () ()
Hydrometer calibration (Tc):	°C   ⇔   °F () ()
Temperature of sample (Ts):	°C   ⇔   °F () ()
Correction (ΔSG):
Corrected specific gravity (SG'):	⇔   points
Plato:	°P(Rule of thumb)
	°P(Lincoln)
	°P(Cubic)
Brix:	°Bx