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Automotive 6 Volt Generator Transistor Voltage Regulator

rjenkinsgb

Well-Known Member
Most Helpful Member
That should work, though I'd move the sounder to pin 7 rather than pin 1; the IC dissipates less power that way.

I cannot see any reason for the previous problem, it sounds like it may have been a faulty pot?
 

Danwvw

Member
Thanks for the reply!
It could be the voltage pot, It's kind of cheap and I had placed o rings that same day between it and the knob to make it stay in position however I did turn it a bunch and test it and push in and pull out etc and it would not act up. It seemed to be pushing on the current pot that was affecting it intermittent but that could be another bad connection not the source of the problem rather a intrerupt to the problem.
So on the LM311 alarm circuit it measured something like 16ma, not sure I understand why it would use more power with the load on pin 1 of the LM311, guess it has in internal resistor to ground on pin 1? But yes, I moved the voltage display and alarm circuit to the switched ignition voltage on the back of the ignition switch and hot glued the Piezo Sound Transducer to the back of the speaker grill behind the dash of the car.
 
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rjenkinsgb

Well-Known Member
Most Helpful Member
not sure I understand why it would use more power with the load on pin 1 of the LM311, guess it has in internal resistor to ground on pin 1
With the output on the emitter, the output stage is being used in "emitter follower" mode and the minimum drop from V+ to the output is over 1.2V as the last transistor is driven by another emitter follower plus further stages.

With the emitter grounded, the output transistor is the only device (other than the current sense resistor) in the output current path and the voltage drop is much smaller, so much lower internal power dissipation in the device, for any given load current; plus more available voltage across the load.

See the full internal schematic on page 10:
 

Danwvw

Member
Thanks for the explanation. The LM311's I have test at about .47 volts on the Emitters as I recall. It's good to know though.
The alarm circuit is not really loud enough and it kind of chirps now and then was worse till I added the capacitors. The only real problem with the alarm is it's hard to hear and at the same frequency of the air leaking around my vent window. It needs more hysteresis as its transition from off to on takes about 200 mv. In the test circuit I thought I saw it loading my 8 volt battery supply more when it was off and this was like hysteresis however on the car it lost that.

I was researching Automotive Alternator Electronic Voltage regulator IC's and they have built in fault sensing etc to make sure they stop the alternator from charging if the conditions are wrong.
As for our Electronic Generator VR design there may be possible ways to design it to not be able to fail High? Or perhaps use a FET that burns out easier than the 6 volt generator.
I have acquired several spare used 6 volt generators and regulators and now am toying with an Idea to build the ELECTRONIC VOLTAGE REGULATORs all open atop the Generators to show-off the electronics rather than potting it inside a old regulator housing. The only HeatSink needed really is the Output Diode but I do like having the MOSFET mounted too. My STPS40L15 O Ring diode is working perfectly with just .32 or so volts Forward with or without the Headlights on even though it just rated at 40 amps.
 

Danwvw

Member
Today out driving around then while pulling in across from the Post Office My Over Voltage Alarm sounded full, I looked down at the VoltMeter, it was going up, 8 then 9 volts. Being in a parking spot I quickly shut the engine off . Got it to work well enough to go home by fiddling with the wires. Pulled the IC Board and found the problem was a connection I had made at the board with telephone wire to the low side of the Voltage Setting Pot It was barely soldered at the board and was loose and twisted around. Replaced the wire with some 18 Gauge Stranded.
All is well again.
 
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Danwvw

Member
Added 2 0.4F @4.5 VDC SuperCapacitors in series to the power at the ignition switched 6 volt where the Alarm Circuit is and it worked nicely to eliminate the noise which was like little crackling sounds the alarm circuit was making. in the 6.8 to 7,2 volt range. Note the car does not shutoff for about 1 second now when the key is turned off. The voltage reading however are a little higher. Just wondering though. Would it be better for the SuperCapacitor if it were on the Un-Switched side of the ignitions switch? It would then stay on all the time but may be harder on the Ignition Switch? Also just wondering, do SuperCapacitor's ever catch fire?
SuperCapacitor.jpg

Voltage_OV_Alarm_Sch0001.JPG
 
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rjenkinsgb

Well-Known Member
Most Helpful Member
Hi Dan,
supercaps can fail from overvoltage, I don't know if they can catch fire.
Possibly a 1A fuse may be an idea, just in case?

With two or more in series, add equalising resistors across them to ensure the voltage across either one does not creep up over time if the leakage is different between the two.
That should hopefully avoid any problems.
 

Danwvw

Member
Thanks for the reply! Maybe they would be best on the headlight or horn circuit, somewhere there is a fuse. I tried a 2.5 ohm varistor in series with them, thought that may provide some protection however even 2.5 ohms was enough to cause them to be ineffective at filtering out the 6 volt power noise so a fuse would probably bring back the noise. Maybe i'll put them in a metal box? I have some 3 volt zeners that I could use across each one however when I took Bal voltage measurements they were all between 2.2 and 2.5 volts on a 9 volt battery without balance resistors, maybe 100K ohm resistors would ballance? Something high so they could be left with the power on all the time?
 
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Danwvw

Member
I have been doing some modeling for a 3rd Prototype that I plan to use on another engine with attention to "Form and Function" and ease of connections.
The plan is to use two circuit boards with the Un-Regulated Power coming up from the bottom board via brass support post that that mount the IC Board on top with Copper Shunt Coils from D+ which will be supported on brass post from the heat sink which will be mounted on 2 hubcap clips with a 6" hose clamp around the generator. The Field Resistor will go on the back side. MOSFET, Output Diode and Field Flywheel Diode on the Heat Sink.
It won't be getting a digital Amp Meter but could. Probably just a Digital Voltmeter so the voltage can be more easily set.
The only wire needed will be the 6 volt switched which I never figured out how to eliminate. DF can go on a brass post while Ground can be made to the Heat Sink and a 10X32 X 2" Brass Screw will carry B+ Output.
Here are the 1st Photos:
ModlingFrontView.jpgModlingBackView.jpgModlingInsideView.jpg .
 

Danwvw

Member
UpDate I have the Power Supply Board the Bottom Board done and did a Mock Up with it installed in the photo below. The Power Supply is changed just a little it's now only got one ripple filter network to save space on the board. Also included a 2.5 ohm Thyristor in series with two zeners in series for a 10 volt limit across the Un-regulated output. Only 1 wire will be needed from the bottom board to the top board it's the 6.2 volt reference supply wire. Other wiring will use the post with DF and D+ on post this will clean it up compared with what's now on the car.
ProtoType3MockUp.jpg
 

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