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Fri May 25, 2018 1:29 pm

Double checked all wiring routing and connectiions...all good. So, unfortunately, I’ll be removing the tach and converter and sending them back to NHS right after the holiday weekend.

As mentioned earlier, I’m concerned that the converter setup for this 12 volt tach hasn’t been fully vetted to insure accurate tach readings on a 6 volt system. I’m also wondering if my pertronix ignition might be compounding the problem.

Hopefully NHS can figure it out. If not, I might decide to go back to a clock. :roll:

Thu May 31, 2018 8:47 pm

Though I'm not putting a tach in right now, some of the other conversation about lights and wiring helped me with my own woes, and I wanted to contribute a little solution I undertook.

The plastic inserts on my taillights were loose and the bulb contactor tended to push the plastic part forward, with a bad connection and dim/failing lights resulting.

After following the tips in this thread and chasing down all my wiring connections, I discovered this issue and applied epoxy to better hold the white plastic parts in place. They're firm now and with the other checking of grounds and contacts I've done, my lights have never worked better.

Thu May 31, 2018 9:16 pm

Epoxy is what I used on mine. It works great. I think the plastic block changes shape with age and can slip out of the crimp. The epoxy fills in the gap once it is wiggled in around the diecast and plastic. I clamped it with a g-clamp to keep it as far back as possible and have the contact spring placed to apply the best tension on the bulb....once the stuff has cured.
Nicholas

Wed Jun 06, 2018 1:06 pm

NHS called me this morning to let me know they,’ve bench tested the tach/converter, made some slight adjustments, and it’s working properly. They’re shipping it back to me today. They also recommended that I make 2 changes to my wiring when I reinstall.

1). Connect the ground to converter wire to a good, clean chassis ground instead of the wiper motor ground strap where I have it connected now.

2). Connect the power to converter wire directly to #15 on the back of the ignition switch instead of the fused side of fuse 8 where I have it connected now.

Am I correct in my understanding that its always best to pull switched power from the fused side of the fuse block? If I pull power directly off the switch, is it adviseable to install an inline fuse? If yes, how many amps?

Wed Jun 06, 2018 2:38 pm

Quote: Am I correct in my understanding that its always best to pull switched power from the fused side of the fuse block? If I pull power directly off the switch, is it adviseable to install an inline fuse? If yes, how many amps?

The power for the coil (choke and electric cutoffs if you have a carburetor) is before any fuses. That's the reason for a fuse for the backup lights. Power to the coil doesn't have one.
As for fuses and sizes. A fuse is to protect the wires not what's after the fuse.

Fri Jun 08, 2018 2:32 pm

The tach came back from NHS today, and I installed it following their recommendation to wire the power wire from terminal 15 on the ignition switch rather than the fuse block, and I moved the ground connection from the wiper motor ground strap to a good clean and tight chassis connection. Unfortunately, the tach still reads too high.

Idling at 850 rpm, tach reads 1,200 with no lights on, 1,100 with park lights on, and 1,000 with headlamps on.

At approx 3,500 rpm, it reads 5,000 with no lights on, 4,500 with park lights on, and 3,800 with headlamps on.

At approx 4,500 rpm, it reads 6,000 with no lights on, 5,200 with park lights on, and 4,800 with headlamps on.

I’m wondering why turning the lights on and off is effecting the tach readings like this....could there be a an issue with either the light switch and or the wiring to and from the light switch???

Or, is the car’s hard start relay somehow causing the tach’s inaccurate readings when the lights are turned off?

Thoughts/recommendations appreciated.

Fri Jun 08, 2018 3:08 pm

Quote: Or, is the car’s hard start relay somehow causing the tach’s inaccurate readings when the lights are turned off?

No! Back when I had a 6v VW. I used a below-dash voltmeter. What I found was 'regular' driving the voltmeter showed about 7v. When I turned on the headlights the voltage would drop to around 6v. When I removed the VR cover and 'made' the small wire relay contacts, the voltage jumped up around 7v again with the headlights on. Turned the headlights off voltage jumped to like 10v. Unmade the contacts voltage back to 7v.

The crew that tested your tach and voltage 'doubler' probably did it on a bench with a constant voltage power supply and a signal generator for the points input.

To sum this up, your input voltage from the generator varies depending on the load it 'senses'. I would suggest a solid state IC 6v voltage regulator for the input to the 'doubler'. OR a solid state IC 12v regulator for the output voltage from the 'doubler'.

This probably is more than you want to do.

Fri Jun 08, 2018 3:45 pm

[quote="runamoc"] Quote:

To sum this up, your input voltage from the generator varies depending on the load it 'senses'. I would suggest a solid state IC 6v voltage regulator for the input to the 'doubler'. OR a solid state IC 12v regulator for the output voltage from the 'doubler'.

This probably is more than you want to do.

Thanks!

Something Like this?

https://www.parts-express.com/7806--6v-voltage-regulator-to-220--7806

If yes, How would I wire/install something like this?

Fri Jun 08, 2018 4:04 pm

[quote="FL-Frank"] runamoc wrote: Quote:

To sum this up, your input voltage from the generator varies depending on the load it 'senses'. I would suggest a solid state IC 6v voltage regulator for the input to the 'doubler'. OR a solid state IC 12v regulator for the output voltage from the 'doubler'.

This probably is more than you want to do.

Thanks!

Something Like this?

https://www.parts-express.com/7806--6v-voltage-regulator-to-220--7806

If yes, How would I wire/install something like this?

Look here for an answer to that....
https://www.robomart.com/l7806-dc-voltage-regulator
It shows disgrams with pin layout and a schematic.
Nicholas

Fri Jun 08, 2018 5:38 pm

Quote: How would I wire/install something like this?

Ignore the 12v description. If the input is over 6v, the output will be regulated to 6v

Fri Jun 08, 2018 5:48 pm

runamoc wrote: Quote: How would I wire/install something like this?

Ignore the 12v description. If the input is over 6v, the output will be regulated to 6v

Thanks,

How are the wires connected to the regulator’s pins? Would butt connectors work like I used to install the inline diode on the signal wire?

No need for a diode like shown on the diagram linked above?

Fri Jun 08, 2018 6:44 pm

FL-Frank wrote: runamoc wrote: Quote: How would I wire/install something like this?

Ignore the 12v description. If the input is over 6v, the output will be regulated to 6v

Thanks,

How are the wires connected to the regulator’s pins? Would butt connectors work like I used to install the inline diode on the signal wire?

No need for a diode like shown on the diagram linked above?

Just solder some wires to them then use some butt connectors to connect it to the voltage doubler input wires. Diode? Not really. A diode is an 'electronic' check valve. Voltage only goes one way. It's already DC going one way. The diode on the signal is needed to block AC and only lets the DC signal thru.

Sat Jun 09, 2018 2:56 am

What does 10uf signify in the diagram?

Sat Jun 09, 2018 4:58 am

uf = microfarad Those are 10 microfarad capacitors.

Sat Jun 09, 2018 5:12 am

Are the capacitors required for my application?

Sat Jun 09, 2018 8:15 am

FL-Frank wrote: Are the capacitors required for my application?

Maybe...capacitors can do two things. They 'pass' AC and they 'store' DC. I think on this circuit they help 'flatten out' any ripple of the DC voltage.

Sat Jun 09, 2018 8:29 am

runamoc wrote: FL-Frank wrote: Are the capacitors required for my application?

Maybe...capacitors can do two things. They 'pass' AC and they 'store' DC. I think on this circuit they help 'flatten out' any ripple of the DC voltage.

This is getting more and more complicated :lol:

Would 16v capacitors suffice? Connect these by soldering also?

Sat Jun 09, 2018 9:50 am

Quote: Would 16v capacitors suffice?

Yes, this # is the maximum operating voltage so you're good on that. If they are electrolytic capacitors you have to be mindful of polarity.

Sat Jun 09, 2018 10:28 am

Would these be good to use?

https://www.amazon.com/gp/product/B071KSXCVJ/ref=ox_sc_act_title_2?smid=AGNQZEOF5D5M3&psc=1

Sat Jun 09, 2018 1:07 pm

“A picture is worth a thousand words”.....

Is this diagram correct for wiring the tach with a diode, the “doubler”, an IC voltage regulator, and a capacitor?

If not, what corrections are needed?