project 1951 Pontiac Chieftain

[PhilA]

Well, tested the ammeter. It's good. Was replaced in 1970 according to the writing on the back.

 

 

Hooked up with a bit of pressure from my tire pump, the oil pressure gauge works.

 

 

Unfortunately, both the fuel and temperature gauge have been hooked up to 12V. The temperature gauge was hazy on the glass. I was wondering why. Well, there's why. It caught fire.

 

Ugh. I hate dumbass people.

 

 

Phil

[PhilA]

Thinking on this front, it looks like the coils will undo.

 

That means I can recalculate the correct resistance to half the current by reducing the wire gauge.

 

Basically, rewind the gauge for 12V and forego the voltage converter.

 

Phil

[LightBulbFun]

Thinking on this front, it looks like the coils will undo.

 

That means I can recalculate the correct resistance to half the current by reducing the wire gauge.

 

Basically, rewind the gauge for 12V and forego the voltage converter.

 

Phil

 

I was about to say dont you have to worry about the inductance of it all but then I realised this is just a DC electromagnet moving a simple needle 

 

it looks simple enough that even if the coil and core was completely toast and ya could not count the windings, that with a small tube/lump of ferrite and some magnet wire you could prolly make your own core n coil

[PhilA]

Yeah, it's two coils at 90 degrees to each other, one having the resistance across it varied to make the iron of the needle move.

 

Simple but effective.

 

The core is the iron bolt. It will have some sort of secondary center but from what I read both coils should be identical resistance, so that makes life a little easier.

 

I think I'll be rewinding these ones.

 

 

Phil

[PhilA]

I started today on the temperature gauge.

 

 

Managed to get one coil out.

 

 

I built a contraption to count the number of turns the drill makes. Made a cammed section on the chuck out of tape, and fixed a microswitch to the metal plate, operated by the cam.

 

 

Many turns!

 

 

All unwound. All burned. So now at least I can solder the three pieces together, measure the resistance now all the windings aren't shorted out.

 

I need to go find my micrometer and see what gauge this wire is also.

 

Phil

[somewhatfoolish]

I started today on the temperature gauge.

 

20181124_133531.jpg

 

Managed to get one coil out.

 

20181124_142308.jpg

 

I built a contraption to count the number of turns the drill makes. Made a cammed section on the chuck out of tape, and fixed a microswitch to the metal plate, operated by the cam.

 

20181124_143200.jpg

 

Many turns!

 

20181124_143205.jpg

 

All unwound. All burned. So now at least I can solder the three pieces together, measure the resistance now all the windings aren't shorted out.

 

I need to go find my micrometer and see what gauge this wire is also.

 

Phil

Quoted so I can like it again.

[hairnet]

*falls over with technicality

[PhilA]

Okay, so that's 33 gauge.

 

 

Now for some calculation. I need to measure the length too.

 

Phil

[vulgalour]

This is ingenious.

[PhilA]

Well, by 1970 this car would have been so so so far out of date, and probably winding down in usage.

 

Only doing what AC Delco did back in the day

 

Phil

[PhilA]

Ok so

 

33 gauge is 206 ohms per 1000'

 

36 gauge is 416 ohms per 1000'

 

Therefore 518 turns of 36AWG should see these coils working again, but for 12V instead of 6V. Ordered some enameled wire, shall rewind it and test. Calibrating the things is gonna be fun though...

 

 

Phil

[Asimo]

Yeah but - same current @ double the voltage means coils will dissipate double the power.

 

Same current, double the turns means armatures will see double the magnetic field strength. Will this matter? Maybe only if something saturates, affecting linearity. Possibly.

 

Not being picky, just enjoying what you are posting!

[PhilA]

Same number of turns, twice the resistance, same current for double the voltage.

 

I'm reducing the wire gauge. Yes, they'll have to dissipate more. I'm going to test run them and check the temperature they operate at.

 

Phil

[DodgeRover]

Wouldn't increasing the resistance decrease current?

V=IR

[PhilA]

Not if you double the voltage from the original design.

[hairnet]

Ok so

 

33 gauge is 206 ohms per 1000'

 

36 gauge is 416 ohms per 1000'

 

Therefore 518 turns of 36AWG should see these coils working again, but for 12V instead of 6V. Ordered some enameled wire, shall rewind it and test. Calibrating the things is gonna be fun though...

 

 

Phil

 

 

Yeah but - same current @ double the voltage means coils will dissipate double the power.

 

Same current, double the turns means armatures will see double the magnetic field strength. Will this matter? Maybe only if something saturates, affecting linearity. Possibly.

 

Not being picky, just enjoying what you are posting!

 

 

Same number of turns, twice the resistance, same current for double the voltage.

 

I'm reducing the wire gauge. Yes, they'll have to dissipate more. I'm going to test run them and check the temperature they operate at.

 

Phil

 

*brainmelt

[LightBulbFun]

*brainmelt

 

 

 

and thats not even getting into things like power factor (or negative resistance) 

 

for example a 40W 4ft T12 Fluorescent tube has a voltage drop of 110V and a rated current of 0.43A but if you do ohms law that comes out to 47W thats because the tube has a power factor of 0.85 so factor that into the maths and you get 110*0.43*0.85=40.2W

[PhilA]

But this is coiled DC pure resistance.

 

Phil

[hairnet]

But this is coiled DC pure resistance.

 

Phil

Nahhhhh

[Crusty Sills]

I'm loving this thread but blow me, I remember why the witch craft of electrics is beyond me!!!

Mechanical work check

Panel work check

Paint check

Electrics fuck right off!!

[Guest Hooli]

Nahhhhh

 

Fucking hell that's an ugly unicorn, no wonder they died out!

[PhilA]

I have been corrected on my physics- double the resistance by halfing the wire cross-section, but also double the number of turns.

 

12V conversions often done to 166% rather than my planned 200% due to the wire not all fitting on the bobbin if you want to wind twice as many turns.

 

I shall experiment and see! Wire is expected to arrive tomorrow.

 

Phil

[purplebargeken]

I understand cleaning interiors, I do not understand whatever you have been saying about electricals. Please stop. It hurts my head. 

[busmansholiday]

I understand cleaning interiors, I do not understand whatever you have been saying about electricals. Please stop. It hurts my head.

No, this is excellent, every day is a school day, and as our safety manager would always say, "there's no such thing as a problem, it's a learning opportunity".

 

The late Dave numbers would have been well impressed.

[LightBulbFun]

have this "crass" meme for when you start work on the Alternator/dynamo 

 

 

(For those who dont know its Fleming's left/right hand rule Motors/generators)

 

as someone who is quite heavily into all things electrical im throughly enjoying the last few posts (well to be fair iv been thoroughly enjoying all the posts on this thread )

[PhilA]

So. I vacuumed the chairs and carpet.

 

 

I shampooed the chairs.

 

 

It's now a more pleasant place to be.

 

 

I need to replace the "Oh s**t!" rope that is meant to go across the back of the front seat though.

 

 

Phil

[hairnet]

limo

[PhilA]

Why you larffin?

[DeeJay]

Rope?

[PhilA]

Rope?

Yup, it was a common thing to put a rope across the back of the rear seat for passengers to grab. From what I see it's meant to be like the type you get at a theater.

 

Phil