GPS speedo

 Toying with some ideas for winter and something to do when I'm away from home - working...

GPS speedo has been a thought, as my speedo needle is a bit vague, has a mind of its own and doesnt do zero.

The mileometer is fairly good though.

Anyway - here it is so far. Using a donor speedo.

with ideas and help from youtube, google and retro-mini.

It may get finished one day.

Or it may just stay on the desk as it is

I took the jaeger gps speedo on holiday to Wales.

It worked rather well I thought. 

If a bit steppy.

Gps speed is updated every second - which can be a long time when accelarating away

Although it matches exactly with google maps speed on the phone.

Miles on the trip meter is calculated every iteration (about 1 second) by the simple method of

distance = speed x time - rather than the haversine method.

In just over a 1000miles it's only 7 miles less than the daily driver so is quite good I think.

I took the jaeger gps speedo on holiday to Wales.
It worked rather well I thought. If a bit steppy.
Gps speed is updated every second - which can be a long time.
Although it matches exactly with google maps speed on the phone.

Miles on the trip meter is calculated every iteration (about 1 second) by the simple method of
distance = speed X time - rather than the haversine method.
In just over a 1000miles it's only 7 miles less than the daily driver so is quite good I think.

The update rate of the gps is every 30s and the arduino has to hang around while it gathers the data so there is always a bit of time when I cant drive the needle.

I'm now working with a Nano ESP32 version, the idea is to use its dual cores and realtime elements to have one core doing the gps and the other doing everything else and consequently able to smooth the step resonse of the needle by using the non blocking update method.and an element of prediction using acceleration.

I should be changing the brake hoses - but its cold outside. 

The next test version took a while.
The ESP32 is a 3.3v system and I need 5V to drive the stepper motor.
Initially had lots of issues with noise until I replced the 8way voltage converter to a 4way version.
Faster GPS module as well (same 1s update but faster to talk to)

Now I have a smooth pointer drive. Non blocking update every 50ms in its own task.
Also saves the lat long (and other data) to SD card so can view on google maps.

Lower display shows the mileage at low speeds and speed in MPH when moving. can be set to KM/h by switch.

Finally managed to read the saved mileage/trip data back from the SD card on power up.
used this as an excuse to buy a 3d printer. its definiteley and expensive speedo.

Will add a pushbutton on a stalk (similar to the original) to reset the trip and change to display to kmph.

I keep having ideas and it keeps me out of the cold.

• Lights on reminder.
• indicators on too long reminder
• day/night brightness

pointer update rate is now 35ms, was a lot smoother at 50ms but then it would lag behind a little.
Can take 30s to get the minimun number of satelites after a long time powered off.
Pointer tuning at low speed still required.

Worked on it a bit more, now have the glass on the front. The needle initially rattled on the window so another re-design needed.
Also needed to install an end stop more subtle than a cocktail stick.
A sewing needle was just the job.
Made a plug for the back of the speedo.
Original plan was to fit the Arduino inside the speedo but for ease of "continuous update" I'll mount it in a box.
trip reset switch (mini pushbutton) comes out of the original trip reset hole.

there's been quite a few updates to the speedo software.
its still working on trial in the daily driver.

Now Ive updated the circuit from breadboard to veroboard.
And created a black box. There is space for more parts.

I need to add wiring for the digital inputs for Ignition and lighting (green bits in photo)
and analogue input wires from fuel guage and water guage.

I dont need the indicator input anymore, the new LED's are like laser beams.

Finally fitted the speedo to the Sunbeam.
Mileage now set to old speedo value.

The GPS sensor seems to be able to still pickup 12 satelites under the dashboard in the garage so maybe I dont need to put the sensor on the dash top.

Added the analog wires(x) for the water temp and Fuel qty and digital wires for Ignition-on and lights-on.
Water temp not really needed but might as well - roughly worked out that the temp(y) is fairly linear so y=mx+c =-.1157x + 142.7.
but that isnt quite right as currently it says the garage is 28 degrees. so it may be almost linear on the guage display range only
When I top up the tank can then work out the graph for Fuel as well. then can monitor the mpg 

a 1 minute video - power on (via extra switch for now), lights on (dim display a bit) and reset trip distance

Drove to Laon Historique 2024 and tracked on the speedo

road test

working well

Servo failure

 It seems my servo is holding on the brakes.

Overheating so much I rolled into park foche Laon with only a hand brake.
After a bit of cooling it was fine for the rest of the day.
Sticking on again at the farmhouse and unlocked when I turned off the engine.
I removed the vacuum hose and blocked it with a tyre valve.

Similar to previous post.. do I need a servo.
Well, with current braking power, yes I do. Quite a struggle to stop.
I have a girling 7/8" master cylinder. Do the none servo cars use a bigger bore?

I'll try the air valve fix first from the archive.
But also, is there a repair kit for the lockheed type 6, 4257 729 29?

Considering I always thought the brakes were a bit hard - so assumed the servo was dud anyway - now it is dud a proper emergency stop would probably break the seats by pushing so hard. So - in my case -  need to fix it.
Of course there may be more wrong than just the servo.

My master cylinder is 7/8" - series I & II had 11/16". So I think to run without servo one ought to use a different master.

This weekend I'll clean and polish the air valve and give it a test run vacuum on.
And a fluid bleed.

I've looked under the air valve and the air valve piston seal is well worn.
So for now I've ordered enough to service what can be accessed easily from northwestclassic.

The proper full service/seal change will be done in the winter.

my servo part number is 4257-729, apparently superseded by 4257-792.

see here for servo operation http://www.mgb-stuff.org.uk/servo.htm

see here for servo rebuild https://landcrabforum.co.uk/thread/393/lockheed-servo-rebuild

on the last run the brakes stuck on again, so I missed a day trip to the National.
Weather is a bit    so pulled it all apart.

The brakes release when the engine is stopped but I'm changing all the seals in both master and servo.
The servo seals looked OK but the master cylinder seals looked life expired.
Also, despite recent bleeding of a pint of fluid, the fluid in the master still looked contaminated.

Will see soon enough. (I had some yellow that needs using up. No-one will notice)

Got it all together after the master cylinder and servo rebuild -a while ago.
Drove out of the garage and the symptoms were the same. - Brakes stayed on and would release with engine off or very low idle.

After some more looking at the drawings and how it works - In desperation (the only thing still- old) rotated the rubber hose that joins the front portion to the airvalve. It then seemed to work well enough to go to Capel car show.

I replaced the rubber hose with new and now it is working as expected - for two good runs at least.

maybe that was it.

My current theory on the hose is that it had hardened to the profile of the air valve and pipe.
So wasn't blocked but leaking. So not enough power to push the air valve back down. (Could be wrong theory)
Rotating it assisted the seal.
The pipe was easy to remove. The new one was a bit of a struggle to fit. So is well and trult sealed.

It's still OK.  
But I realise now the brake effectiveness is a bit sh t. Even with the servo.

Looking at EBC front and rear next. or Princess 4 pots.

10 volt regulator

 I've had the new regulator in the box since 2016.

The old regulator was working OK. but after some issues trying to measure the voltage I decided the time had come to install.

For curiosity I attached the scope to see the differences.
The old bimetallic system works by switching 12V on and off resulting in an average of 10V.
Fuel gauge shows 4 gallons.

The new one works by magic and outputs 9.9V constantly
Fuel gauge shows 3.5 gallons.

When it stops raining it will be interesting to see the indicated temperature and then measure the water temp by another means.

decided to make my own with a 10V regulator chip and an indicator LED

similar guide here Voltage-Regulator.htm

The regulator is working well with a constant 9.9V output but now I need to adjust the fuel and temp guages :-( 

Prepare for the Laon 2023

Laon 2023 was a good event 

I even made the local paper.

- marked by the Sunbeam servo failing to release the brakes and cooking the fluid. undoing the vacuum fixed that issue but the pressure needed to operate the brakes was more than expected.

Had a good time in Laon but after the day driving around the city the Alternator light started to flash and the voltmeter change between 12v and 14v in sequence.
The next day was a drive to Honfleur but wasnt long before the warning light came on and the voltage started to go down. I stopped to investigate properly when it got to 11v and it had difficulty starting.

Thinking Alternator I checked the voltage at the exciter pin (small wire). Nothing.
So hot wired from 12V battery bus direct. And off we went again.
This wire needed to be disconnected every long stop.

10 minutes later the engine cut out and we rolled to a stop. Engine would start on the key but stop when released.

Under dash found burnt white wires on the run contact of the ignition switch. Mostly white wires melted together. (probably others but thats for tomorrow).
Removed these wires from ignition switch and slaved in a new cable to the fuse box.

Then we were able to carry on to Honfluer.

I did try the Alternator exciter wire direct to the switched 12v - but then the engine wouldnt stop  
Add a warning bulb in circuit and it would stop.
Funny things alternators

Added a fuse box inside the regulator box for the 12v Live circuit (Lights, Horn relays, hazards etc).
Another for the  Switched 12V. I need to extend a few wires now.

The fuse blown indicators don't work on LED sidelights but do work on incandescent dip/main.
Will check later if works with LED indicators (due to dashboard warning lamp providing the circuit)

 

The solenoid switch failed just before Laon. Probably been bad a long time.

It was probably dirty contacts inside. Anyway a new one fixed it.

I fed a new wire to the starter motor a few years ago - probably was the solenoid even then.