Automobile voltage regulator usefulness and pinouts - Page 1
Forum section: electronics / projects

author: proschuno
author_rank: Contributor
timestamp: March 07, 2014, 03:14:21 pm
content: So a while back I obtained these automobile voltage regulators from a friend, and I just simply would like to know if anybody can figure out the pinouts on these guys, and what kind of regulated voltages to expect from them.In the photo below, from the left the first two regulators say VR-38 Echlin, the next says TP-50 (this says "electronic control circuit"; don't know if this could mean it's not a voltage regulator but something else). The last says vr 148 for those who can't read it.

author: Stonent
author_rank: Super Contributor
timestamp: March 07, 2014, 04:28:38 pm
content: What did they come from? The pinout is likely in the service manual for that car.

author: dannyf
author_rank: Super Contributor
timestamp: March 07, 2014, 05:27:22 pm
content: QuoteWould a meter do a better job there than the rest of us can remotely?

author: Neverther
author_rank: Regular Contributor
timestamp: March 07, 2014, 05:53:21 pm
content: Alternator vregs or generator vregs?Alternator vregs are pretty simple:Rectified voltage from its own diode is fed into comparator (1-4 phase rectifier is for actual output), if voltage is under setpoint, feed said voltage via transistor or whatever to the rotor electromagnet. If voltage is too big, dont feed the voltage to the rotor coil. Usually its configured so it doesnt oscillate.If there is no rectified voltage, you can rev the alternator until residual magnetism wakes it up, but usually they have the initial exiting provided by the idiotlight (enough exitement for the vreg to start operating, diode from fields drives this high so idiotlight goes out).2 connectors for brushes (or 1 if ground is shared)1 connection for exiter (idiotlight)1 ground1 for output/battery connection (depends on setup)1 for stator/fields connection (usually internal diode, provides power for rotor coil, depends on setup).Battery power never drives the rotor coil directly as that is just asking for trouble (maybe Lucas....).I've tested couple with variable power supply (feed voltage into field input and measure when voltage on brushes drops down, I think I had 15ohm load resistor connected to brushes).Generator vregs are a lot different as permanent magnet generators just spits out stuff depending on speed.Remember: like DC motors so no rectifiers, no diodes (alteast in the old ones).This is just example as there are many ways this was done.They usually have a relay system that feeds from the generator.When voltage is under battery voltage the relay is open (car not running, no need to connect battery to generator coil to waste power, closed when voltage is good). If voltage is high, throw relay contacts to incude resistor in series. If voltage is dangerously high, disconnect with relay.Usually 3 connections: ground, generator positive, battery positive (or opposite if system is running positive ground).May have external load resistors but thats pretty rare as generators are rather weak.Never tested one as they either work or dont, voltage to generator in should engage relays depending on voltage.Edit:Ok had old Lucas 127 alternator regulator hanging around and it only has fields in, gound and one brush connection, the idiotlight (excitement) is connected directly to brush and the light goes out when the rotor has high current (voltage) across it.

author: Joule Thief
author_rank: Regular Contributor
timestamp: March 07, 2014, 07:02:01 pm
content: Tryhttp://www.wellsve.com/custom_searches/cross_reference.php?part=vr-38&submit.x=0&submit.y=0your other parts may also cross reference to Wells productsthen goto pinouts herehttp://www.wellsve.com/custom_searches/ds_pinouts2.php

author: proschuno
author_rank: Contributor
timestamp: March 07, 2014, 08:47:25 pm
content: Quote from: Neverther on March 07, 2014, 05:53:21 pmI believe that these are alternator VregsAnd thanks for the links Joule Thief.So given the pinouts in the link:http://www.wellsve.com/custom_searches/showpinoutdiagram.php?partno=VR733#zoom=100would the "batter positive" pin be the input and the "field alternator winding" be the output, the casing being the ground??

author: Joule Thief
author_rank: Regular Contributor
timestamp: March 07, 2014, 09:28:48 pm
content: Switched battery positive terminal will be connected to the ignition switch. This connection power the VR and monitors battery voltage.The field connection is the output to the alternator- provides the proper alternator drive to keep the battery voltage at 13.6 - 14.5 volts

author: Neverther
author_rank: Regular Contributor
timestamp: March 08, 2014, 08:14:45 am
content: Ok english is not my native so the post above has wrong terms when talking about fields :pI assume that the field winding in that picture is the rotor electromagnet feed.Current goes through rotor coil, it creates rotating magnetic field and that creates currents in stator windings.Vreg regulates the current going into the rotor coil: more current -> bigger magnetic field -> more current out of stator.You can think that vreg as big comparator/open loop opamp, the battery positive is the inverting input, and the field winding is the output (driven from battery positive with transistor so it wont go above it). The noninverting input is internal reference voltage.That is the type of regulator I don't like as it feeds directly from battery all the time ignition is on.It doesn't have output for charging light, but the car/whatever propably has real voltmeter on dash to monitor voltage.

author: proschuno
author_rank: Contributor
timestamp: March 09, 2014, 02:08:11 am
content: So the exact voltages I can expect this to output are dependent on the exact design of alternator?

author: Neverther
author_rank: Regular Contributor
timestamp: March 09, 2014, 08:15:26 am
content: Yes, also there are different versions of regulators for colder climates that output higher voltages.I know that atleast some marelli vregs have builtin temperature compensation for similar operation.I've cheated those with separate stator input by using additional dide to output higher voltage.