Permanent fix (in progress): Fuel/temp gauge spiking (pics, not dialup friendly) (3 Viewers)

[snowakii]

The most frequent process errors I've seen (and done) with etching are not enough of an exposure if using photo resist and not sufficiently thick and uniform resist if using pens to draw the circuit. Photo resist is preferred for making multiple boards. You can even use a program like visio to draw the circuit traces if you don't have a PCB program... and of course edit it more easily than laying it out each time.

If your etching is mostly done but there are a few small areas that have not completely been removed, you can just drop etchant on those spots with a Q-tip to avoid over etching the rest. Good luck.. It was fun making the boards I recent did. Something satisfying about having a sheet with 40 or so stamp sized little boards all shiny and identical.

 

[Spudman]

I can never seem to workout these electrical bugs, so I was just going to buy a couple of aftermarket gauges and use them, I am so glad I joined mud, this fantastic, I'll be standing in line for these, thanks spook

 

[Spook50]

Really cool seeing the positive response this is getting. It's a great motivator

In a minor update, I botched my first etching job bigtime last night. My own fault though. I just left the board in brand new solution too long and it took ALL the copper from both sides, traces and all. Hopefully I'll get a chance to get out there tonight and give it a couple more tries. I picked up a larger 2-sided copper clad PCB that I'm cutting into small sections before etching, so any failures are just that one piece, and not a whole board. I'll get the hang of it soon enough I'm sure. Just need to get a feel for it.

Also, muriatic acid is some pretty nasty stuff. Let's just say even with taking precautions, now my floor has a clean-ish spot

 

[snowakii]

Um. Why are you using muriatic acid? That is bad stuff. Feric chloride is much less aggressive. So easier to control. There's another chloride too which I have forgotten which is even slower, but it has the advantage over ferric chloride in that it is clear so you can watch the progress.

Since you obviously already have the muriatic, you might want to dilute that quite a bit. Also with such a strong acid you may need to ensure the etch resist can take it.

 

[Spook50]

Um. Why are you using muriatic acid? That is bad stuff. Feric chloride is much less aggressive. So easier to control. There's another chloride too which I have forgotten which is even slower, but it has the advantage over ferric chloride in that it is clear so you can watch the progress.

Since you obviously already have the muriatic, you might want to dilute that quite a bit. Also with such a strong acid you may need to ensure the etch resist can take it.

It's actually a 2:1 mix of hydrogen peroxide and muriatic acid that uses the copper dissolved in the etching process to make a cupric chloride etchant. I had read about it here and wanted to give it a try, since it'll only be used on boards that I myself will be using for my prototyping.

It worked. Whoa yeah, it worked. I just got distracted by a sudden, uhhh, call of nature you might say. The type that really doesn't take well to waiting. And when I came back all the copper on the one piece went bye-bye (kind of expected it though given the nature of the distraction). Fortunately it was just one piece so I'm not really out anything.

The fun continues!

 

[Spook50]

Update

Haven't had a chance to try etching any more PCBs yet, but hopefully this week I'll have a board for prototype 3. A buddy of mine gave me an old bench mount jigsaw so now I've got something that'll allow me to cut nonstandard shapes.

My original idea to have wires secured to the boards still left a potential failure point that could give way during shipping or even the jostling around necessary to reinstall the dash, so I redrew my board layout for the third prototype. This should not only eliminate the failure point but will give the regulator a much more stable mount to the gauge assembly.

This one still uses a linear regulator and thru-hole components, but my next Digikey order will be the components I need to set up a test rig for a switching regulator.

Pic of the new design for prototype 3:

 

[FJ60Seth]

I've supported your Kickstarter Campaign. Thank you.

 

[Dynosoar]

I just supported your KICKSTARTER too!

Now get back to work!

Dyno

 

[EyeCruzr]

Just joined in on the fun at Kickstarter!!

Thanks!

Ted

 

[Spook50]

Thanks for the support! I've still got a ways to go, but I'm keeping my fingers crossed that it's successful.

Meanwhile, I managed to make a little more progress in the last couple nights. Now that I can do my own PCB etching at home, I have a little better capability for prototyping. I can still only do simple circuits since all my stuff has to be hand drawn by Sharpie (no good enough laserjet that I have access to) and I'm not exactly an artist here. But the stuff is at least functional, which will tell me exactly what I need to know when I do a real-world test (as opposed to just a function test on my bench).

My first successful etching job. Took me a couple tries to get it, but now I've got it figured out. Not pretty, but it'll do its job.



Prototype 3 populated, trimmed down and ready for installation. Hopefully I can get my dash back together this afternoon for a test run. Notice the trimmer pot I installed also. This will let me adjust the resistance on the signal lead which will adjust the output voltage of the regulator assembly. Now I won't have to keep putting together whole new units to get the voltage dialed in perfectly, which will help speed up the process.



Unfortunately I still have to keep tearing into my dash to adjust it. I could've used a couple long wires and remotely mounted the trimmer, but I'll need to test the voltage with my multimeter anyway each time I adjust the regulator, so it would've been a waste of effort. My dash plastic is obliterated though. Time to try tracking down some good condition plastic....

 

[snowakii]

If the laser jet is holding you back, an inkjet will work well enough for what you are doing. Your traces are wide enough and separated far enough to not need a laser jet. Print it out on plain, but good paper and have kinko's copy it to transparency. Just make sure you f"lip" the image when they copy it, which is a setting they have on their copiers. you will have to tell them that very specifically because they will tell you to just flip the transparency over.

For over head projectors that is fine, but you want the ink side right next to the board you are going to expose. Use a sheet od plexiglass to hold it right against the board flat.

or keep shapie-ing it

Good progress.

 

[Spook50]

If the laser jet is holding you back, an inkjet will work well enough for what you are doing. Your traces are wide enough and separated far enough to not need a laser jet. Print it out on plain, but good paper and have kinko's copy it to transparency. Just make sure you f"lip" the image when they copy it, which is a setting they have on their copiers. you will have to tell them that very specifically because they will tell you to just flip the transparency over.

For over head projectors that is fine, but you want the ink side right next to the board you are going to expose. Use a sheet od plexiglass to hold it right against the board flat.

or keep shapie-ing it

Good progress.

The UV exposure method is ideally what I'd rather do since from what I've heard it's more reliable than toner transfer. At some point I'll build a UV box so I can start going that route. It would definitely let me make cleaner traces.

 

[snowakii]

For the size of project you are doing there is a great big uv source readily available.... that big bright thing in the sky. And it is free

 

[Spook50]

For the size of project you are doing there is a great big uv source readily available.... that big bright thing in the sky. And it is free

Not so much during the fall in the inland Northwest

That's really not a bad idea though, using sunlight for the UV exposure. I might have to give it a try when we get a sunny day again if I can get some photosensitive stuff.

 

[snowakii]

I've had good luck on sunny days. Two minutes. Summertime, one minute exposure. Clouds really do affect the needed exposure time. ~2-4 X and I have not gotten good results on cloudy days.

The good thing about the photo sensitive stuff is once you have your mask making multiples is a piece if cake.

 

[Spook50]

I've had good luck on sunny days. Two minutes. Summertime, one minute exposure. Clouds really do affect the needed exposure time. ~2-4 X and I have not gotten good results on cloudy days.

The good thing about the photo sensitive stuff is once you have your mask making multiples is a piece if cake.

I'll have to give it a shot. You're right, it does seem like a much better way to produce my own PCBs. Be great if I could use this method for the real small SMT stuff so I can verify that my circuit works without the cost and time of ordering a small prototype batch from the PCB manufacturer.

Just a few more pics real quick. I love how this new design is working out. VERY solid, good electrical contact, and doesn't protrude back nearly as much as the previous two. No side protrusion at all either. Ran out of daylight before I could get my dash back together, but maybe that'll give me an opportunity to try to repair some of the annihilated plastic from the HVAC trim piece tonight



I had to space it up just a bit with washers so the solder joints wouldn't be stressed (and to avoid bending the PCB to get a secure electrical connection). My goal is for the production units to have nothing on the bottom so no washers will be needed (nor will longer screws be needed for the voltmeter terminals, like I used for this one).


Compact and sturdy!

 

[snowakii]

Here's a pic of a sheet of surface mount boards I made with this method. There are 43 identical circuits. Resistors are 1206 footprint transistors are SOT-23. to avoid having to drill holes, there are pads for wires to be soldered to. So these boards have a combination of fine and wide traces. The sheet is 6" x 9" for scale and still has some remnants of the photo resist, hence the bluish tints in places.

All parts were then hand placed and soldered in an oven.... $50 toaster oven with infrared, but hot air gun works too. For smaller runs you can use a regular soldering iron with solder paste as long as you hold the part down while the iron is applied or else when you lift the iron the part will usually stick to the iron instead of the board.

The other fine parallel lines between each board where the aid in separating the small boards. In your case you may want to get the double sided copper clad to provide your mounting holes better connection depending on which side the surface mounted parts are mounted..

 

[Spudman]

Spook

Excuse my ignorance mate, but my electrical skills are not too good, so this thingy you've made just screws onto the back of the big combination gauge and bob's your uncle no more spikes in the temp and fuel gauge

Thanks

Ivan

 

[TommyLJ70]

can this work on hj60 with 24v ass whell??

 

[Spook50]

Spook

Excuse my ignorance mate, but my electrical skills are not too good, so this thingy you've made just screws onto the back of the big combination gauge and bob's your uncle no more spikes in the temp and fuel gauge

Thanks

Ivan

That's pretty much it. The only extra thing you have to do is disable the circuit that goes through the mechanical voltage regulator, which can be done by putting an insulator of some sort between the breaker points or even (though this method is permanent) just cutting the trace on the factory PCB that feeds 12V to the mechanical regulator.

Tommy, not knowing how 70 series gauges are built, I honestly couldn't say if this regulator would work with them or not. As far as voltages are concerned (depending on what voltage your gauges takes, if it even is different from 12V Cruisers), it would work. I'm just not sure if it would bolt on to any other model's gauge assembly like I designed it to for 60/62 trucks.