Here's a schematic for testing the alternator(s)
discussed in this thread.
Comments Welcome!
Alternator Controller Mk.I
Alternator Controller Mk.I
Greetings,
Here's a schematic for testing the alternator(s)
discussed in this thread.
Comments Welcome!
Here's a schematic for testing the alternator(s)
discussed in this thread.
Comments Welcome!
Hi Peter.
Were you asking for comments?
The 7805 (IC1) used for the 10V regulator needs 2 to 2.3 volts of headroom. Adding the minimum 0.6 drop across D41. This means that you have to be sure that the 12V battery has at least 13.6 to 14V.
The DC gain of a 2N3055 can go as low as 5-20. When it's turned fully on by a 390 ohm resistor R8 between the base and 12V, you are only guaranteed 150 mA maximum current through the field winding only when the voltage across R8 is high. Probably more will flow, but a Darlington transistor might work better here or just redesign the circuit to have Q2 drive the LOW side of the field winding, like the Delcotron regulators.
The circuit works by comparing the attenuated voltage across the field winding with that voltage at the adjustment R3, so that you are able to control the field voltage from about 3.5V to 16V, if 16V were available.
Why does the circuit just adjust field voltage? There is no current regulation here.
Just curious. I'm going to post my own circuit for analog control of stepping motors here soon. I hope to get some comments on that one.
Bob
[/i]
Were you asking for comments?
The 7805 (IC1) used for the 10V regulator needs 2 to 2.3 volts of headroom. Adding the minimum 0.6 drop across D41. This means that you have to be sure that the 12V battery has at least 13.6 to 14V.
The DC gain of a 2N3055 can go as low as 5-20. When it's turned fully on by a 390 ohm resistor R8 between the base and 12V, you are only guaranteed 150 mA maximum current through the field winding only when the voltage across R8 is high. Probably more will flow, but a Darlington transistor might work better here or just redesign the circuit to have Q2 drive the LOW side of the field winding, like the Delcotron regulators.
The circuit works by comparing the attenuated voltage across the field winding with that voltage at the adjustment R3, so that you are able to control the field voltage from about 3.5V to 16V, if 16V were available.
Why does the circuit just adjust field voltage? There is no current regulation here.
Just curious. I'm going to post my own circuit for analog control of stepping motors here soon. I hope to get some comments on that one.
Bob
[/i]
Greetings Bob,
This circuit was drawn on a bar napkin while I was
chewing over the OP's project. I haven't done any
SPICE or breadboarding.
would be a better choice for production.
to use parts with Radio Shack in mind, hoping the OP
would play along and build a breadboard.
I was lead to think the earthy end of the exciter winding
was bonded to the frame, so only a high-side driver
would work. I saw the autozone/GM schematic after
posting this design...
residual magnetism, so the exciter doesn't need to go
to zero volts. Plus, at this point we only have the
battery voltage, so it's hard to drive the single-ended
output to ground in a simple design.
hope the OP does some testing. This circuit is to get
the Alternator up and running. I have a "Mk.II" and
"Mk.III" design on another bar napkin for output
voltage loop feedback and load current loop feedback.
The OP is heading to a multiple Alternator load sharing
solution.
Comments (still) Welcome!
Comments always welcome!Bob Scott wrote: Were you asking for comments?
This circuit was drawn on a bar napkin while I was
chewing over the OP's project. I haven't done any
SPICE or breadboarding.
Correct. I had the L7805 handy in EAGLE, but an LDOBob Scott wrote:The 7805 (IC1) used for the 10V regulator needs 2 to 2.3 volts of headroom. Adding the minimum 0.6 drop across D41. This means that you have to be sure that the 12V battery has at least 13.6 to 14V.
would be a better choice for production.
I used 20 - 70 for HFE from the ON datasheet. I was tryingBob Scott wrote:The DC gain of a 2N3055 can go as low as 5-20. When it's turned fully on by a 390 ohm resistor R8 between the base and 12V, you are only guaranteed 150 mA maximum current through the field winding only when the voltage across R8 is high. Probably more will flow, but a Darlington transistor might work better here or just redesign the circuit to have Q2 drive the LOW side of the field winding, like the Delcotron regulators.
to use parts with Radio Shack in mind, hoping the OP
would play along and build a breadboard.
I was lead to think the earthy end of the exciter winding
was bonded to the frame, so only a high-side driver
would work. I saw the autozone/GM schematic after
posting this design...
Correct. We know the Alternator will come to life fromBob Scott wrote:The circuit works by comparing the attenuated voltage across the field winding with that voltage at the adjustment R3, so that you are able to control the field voltage from about 3.5V to 16V, if 16V were available.
residual magnetism, so the exciter doesn't need to go
to zero volts. Plus, at this point we only have the
battery voltage, so it's hard to drive the single-ended
output to ground in a simple design.
We don't have data on the specific Alternator, so IBob Scott wrote:Why does the circuit just adjust field voltage? There is no current regulation here.
hope the OP does some testing. This circuit is to get
the Alternator up and running. I have a "Mk.II" and
"Mk.III" design on another bar napkin for output
voltage loop feedback and load current loop feedback.
The OP is heading to a multiple Alternator load sharing
solution.
No problem!Bob Scott wrote:Just curious. I'm going to post my own circuit for analog control of stepping motors here soon. I hope to get some comments on that one.
Comments (still) Welcome!
Peter,
I've got an AC motor that I can drive an alternator with which I'll use as a test apparatus between now and when I actually mount up my gas engine.
With the circuit you laid out here, I'll be getting you readings from the leads marked +5v and +10v and armed with them, we'll have more clues as to how to drive the exciter with a micro-controller, no?
Anyway, I'll run to Fry's and pick up these pieces. Do Bob's comments change my shopping list?
I've got an AC motor that I can drive an alternator with which I'll use as a test apparatus between now and when I actually mount up my gas engine.
With the circuit you laid out here, I'll be getting you readings from the leads marked +5v and +10v and armed with them, we'll have more clues as to how to drive the exciter with a micro-controller, no?
Anyway, I'll run to Fry's and pick up these pieces. Do Bob's comments change my shopping list?
Kurt - SF Bay
Greetings Kurt,
work around is to change the pulley sizes, assuming its
belt driven.
(Its two five volt regulators stacked together). The 5V is our
reference voltage. The servo loops will adjust to match the
five volts, so if we had for example a loop gain of 2.4 (12/5
ratio), the output would settle at 12V to be in balance.
The 10V regulated supply is to drive the electronics. That
Op Amp is only rated to 16V, so a floating battery or other
error would threaten it.
At a later date we can close the larger loops around
the Alternator output to give voltage and current sharing
regulation. Also, the voltages can be sucked into a uC with
internal ADC, to digital data. The 5V regulator will power
the uC and other circuitry.
Fry's is walking distance from here.
You should find most of the parts there, but if you're
in the South Bay consider HSC (Halted) and/or
Excess Solutions.
(You probably know these emporiums...)
I was just sitting here thinking that Bob's suggestions
would lead to a modification. Q2 (currently an NPN)
could be a PNP (MJE2955) and the Op Amp inputs
swapped. A few resistors may require tweaking.
Also, it'll need a heatsink (could dissipate 10Watts).
I was trying to Google the 7078 Alternator and see if
the exciter coil is indeed bonded to the chassis. If not
other options open up.
One other thing. The diagram doesn't show any connection
to the Alternator outputs. The idea is that a dummy load
must always be connected, as a free-running Alternator
may fry the internal diodes.
I had in mind a bank of headlights, possibly with some
switches to select one or two sets. Placing two bulbs in
series (at a minimum) would protect them if we got the
Alternator output over 12V while testing it. (Two 12V
55W headlight bulbs for example).
Comments Welcome!
That would work, but an AC motor is single speed. Akheston wrote:I've got an AC motor that I can drive an alternator with which I'll use as a test apparatus between now and when I actually mount up my gas engine.
work around is to change the pulley sizes, assuming its
belt driven.
The +5V and +10V rails are regulated from the 12V battery.kheston wrote:With the circuit you laid out here, I'll be getting you readings from the leads marked +5v and +10v and armed with them, we'll have more clues as to how to drive the exciter with a micro-controller, no?
(Its two five volt regulators stacked together). The 5V is our
reference voltage. The servo loops will adjust to match the
five volts, so if we had for example a loop gain of 2.4 (12/5
ratio), the output would settle at 12V to be in balance.
The 10V regulated supply is to drive the electronics. That
Op Amp is only rated to 16V, so a floating battery or other
error would threaten it.
At a later date we can close the larger loops around
the Alternator output to give voltage and current sharing
regulation. Also, the voltages can be sucked into a uC with
internal ADC, to digital data. The 5V regulator will power
the uC and other circuitry.
We must be neighbours, more or less? The Campbellkheston wrote:Anyway, I'll run to Fry's and pick up these pieces. Do Bob's comments change my shopping list?
Fry's is walking distance from here.
You should find most of the parts there, but if you're
in the South Bay consider HSC (Halted) and/or
Excess Solutions.
(You probably know these emporiums...)
I was just sitting here thinking that Bob's suggestions
would lead to a modification. Q2 (currently an NPN)
could be a PNP (MJE2955) and the Op Amp inputs
swapped. A few resistors may require tweaking.
Also, it'll need a heatsink (could dissipate 10Watts).
I was trying to Google the 7078 Alternator and see if
the exciter coil is indeed bonded to the chassis. If not
other options open up.
One other thing. The diagram doesn't show any connection
to the Alternator outputs. The idea is that a dummy load
must always be connected, as a free-running Alternator
may fry the internal diodes.
I had in mind a bank of headlights, possibly with some
switches to select one or two sets. Placing two bulbs in
series (at a minimum) would protect them if we got the
Alternator output over 12V while testing it. (Two 12V
55W headlight bulbs for example).
Comments Welcome!
I'm closer to the Fremont Fry's, but I used to work down by you. Fry's is horrible about keeping their shelves filled with electronic components like these, but I'll try them first. Maybe I won't have to drive down into the south bay.
I went down to the parts store and picked up a test specimen. Here are some pics of a Lester 7078: http://delanobay.com/alt7078
You'll see the other side of the field (exciter) feed is definitely grounded.
Looks like I'm going to have to build my motor and alternator brackets now. I don't have a way of varying the speed (no pulleys lying around, really). Was hoping to put it off another weekend or two while building controls. Not a big deal. I need to hit ALCO in Oakland for a big plate of steel and OSH for some good reciprocating saw blades. The rest is sweat and hang-knuckles.
Any idea how I can hook up a quick tach? I'd imagine we'd like to know how the circuit is going to behave across the RPM range (and to know what the range is). The kill wire on the engine pulses with each spark. Easy to feed it to a serial port without frying it? Probably not. Google here I come...
A multi-bulb lamp might serve as a good safety load. I think I've got one laying around.
I went down to the parts store and picked up a test specimen. Here are some pics of a Lester 7078: http://delanobay.com/alt7078
You'll see the other side of the field (exciter) feed is definitely grounded.
Looks like I'm going to have to build my motor and alternator brackets now. I don't have a way of varying the speed (no pulleys lying around, really). Was hoping to put it off another weekend or two while building controls. Not a big deal. I need to hit ALCO in Oakland for a big plate of steel and OSH for some good reciprocating saw blades. The rest is sweat and hang-knuckles.
Any idea how I can hook up a quick tach? I'd imagine we'd like to know how the circuit is going to behave across the RPM range (and to know what the range is). The kill wire on the engine pulses with each spark. Easy to feed it to a serial port without frying it? Probably not. Google here I come...
A multi-bulb lamp might serve as a good safety load. I think I've got one laying around.
Kurt - SF Bay
Greetings Kurt,
one end is grounded. Also, the black rectangle looks like
a physical place holder for the AC (3 phase) wiring? Not
sure about the other black rectangle on the output terminals?
do you need to bolt it all together? What I had in mind is
a test stand with an AC induction motor (or better yet a
universal motor and variac) around 1/2 - 1hp. Place this
at the base and have a vertical frame to hold two
alternators (one to start with). Changing the V-belt
would accomodate one or two alternators, and you might
need an idler pulley to tension the belt.
Have you visited Triangle Machine in San Jose? They
break down industrial equipment and machine tools and
sell the components.
proportional to three times the shaft speed, which can be
massaged and used to drive your uC or freq meter.
Secondly, an opto detector using a reflective label on the
pulley(s). The VW genset (that you linked) used this method.
If a car vehicle engine idles at 600 - 800 RPM and produces
peak torque at 2800 - 3500 RPM the crankshaft would
produce a signal at 10 - 13Hz up to 35 - 58Hz. The pulley
ratios turns the alternator at 2 to 2.5 times this speed so
you are looking at about 25Hz (idle) to about 120Hz.
This is the familiar alternator whine that can get into the
vehicle's audio system.
Comments Welcome!
Probably my favourite "themed store"...kheston wrote: I'm closer to the Fremont Fry's
Very clean! Confirms that the rotor is live (slip-rings) andkheston wrote: I went down to the parts store and picked up a test specimen. Here are some pics of a Lester 7078
one end is grounded. Also, the black rectangle looks like
a physical place holder for the AC (3 phase) wiring? Not
sure about the other black rectangle on the output terminals?
I'm not sure what tools you have, can you do welding orkheston wrote: Looks like I'm going to have to build my motor and alternator brackets now. I don't have a way of varying the speed (no pulleys lying around, really).
do you need to bolt it all together? What I had in mind is
a test stand with an AC induction motor (or better yet a
universal motor and variac) around 1/2 - 1hp. Place this
at the base and have a vertical frame to hold two
alternators (one to start with). Changing the V-belt
would accomodate one or two alternators, and you might
need an idler pulley to tension the belt.
Have you visited Triangle Machine in San Jose? They
break down industrial equipment and machine tools and
sell the components.
Two suggestions. Firstly, the alternator will have an AC ripplekheston wrote:Any idea how I can hook up a quick tach? I'd imagine we'd like to know how the circuit is going to behave across the RPM range (and to know what the range is).
proportional to three times the shaft speed, which can be
massaged and used to drive your uC or freq meter.
Secondly, an opto detector using a reflective label on the
pulley(s). The VW genset (that you linked) used this method.
If a car vehicle engine idles at 600 - 800 RPM and produces
peak torque at 2800 - 3500 RPM the crankshaft would
produce a signal at 10 - 13Hz up to 35 - 58Hz. The pulley
ratios turns the alternator at 2 to 2.5 times this speed so
you are looking at about 25Hz (idle) to about 120Hz.
This is the familiar alternator whine that can get into the
vehicle's audio system.
Comments Welcome!
I bolted my project together and started it up today. The alternators appear to perform magnificently together.
Not sure exactly what the RPM was, but at half throttle with all four field wires connected directly to 12v (full-blast), my readings were:
18.5V / 220A
Looks like I've built myself a 4kw DC generator, time will tell how durable it is. Didn't run it very long...don't want to fry my deep-cycle batteries.
Here are some pics:
TODOs before building a controller and a shed for the unit:
- figure out a way to get an accurate RPM reading that I can hopefully port for use with the eventual microcontroller
- build the custom Bigglez test circuit and try it out
Not sure exactly what the RPM was, but at half throttle with all four field wires connected directly to 12v (full-blast), my readings were:
18.5V / 220A
Looks like I've built myself a 4kw DC generator, time will tell how durable it is. Didn't run it very long...don't want to fry my deep-cycle batteries.
Here are some pics:
TODOs before building a controller and a shed for the unit:
- figure out a way to get an accurate RPM reading that I can hopefully port for use with the eventual microcontroller
- build the custom Bigglez test circuit and try it out
Kurt - SF Bay
Greetings Kurt,
While you're at it, can you measure the current in to the field
winding (of one alternator) when it's running? (I assume you
connected the field to a battery first? We need the field coil
current and voltage for completeness).
What's the hp rating of that engine?
If you run one alternator and use your DMM on AC volts
can you measure the ripple voltage? If you DMM allows
frequency measurements, that will tell also you the engine
RPM without further complication.
Comments Welcome!
Excellent! How did you measure the current? Into the battery bank?kheston wrote:I bolted my project together and started it up today. ....my readings were: 18.5V / 220A
While you're at it, can you measure the current in to the field
winding (of one alternator) when it's running? (I assume you
connected the field to a battery first? We need the field coil
current and voltage for completeness).
What's the hp rating of that engine?
If you run one alternator and use your DMM on AC volts
can you measure the ripple voltage? If you DMM allows
frequency measurements, that will tell also you the engine
RPM without further complication.
Comments Welcome!
I bought a DMM today with a DC current clamp sensor and clamped around the 4 gauge battery cable between the unit and the battery bank (2-12v deep-cycles). This is where I got the 220a reading. Worked great! The 18.5v was measured across the battery terminals right thereafter.
I saw your post about checking the ripple frequency and dividing but didn't think to look at my new DMM to see if it had a frequency counter until you mentioned it again. It's got one! I'll give it a try tomorrow.
I'm not sure whether I'll get the resolution I need from the clamp if I use it on the field wire, but I'll give it a shot (it's got 40a and 400a range settings). I've another DMM with a 1A-max current reading capability that I can use, too, if the clamp isn't sensitive enough.
I saw your post about checking the ripple frequency and dividing but didn't think to look at my new DMM to see if it had a frequency counter until you mentioned it again. It's got one! I'll give it a try tomorrow.
I'm not sure whether I'll get the resolution I need from the clamp if I use it on the field wire, but I'll give it a shot (it's got 40a and 400a range settings). I've another DMM with a 1A-max current reading capability that I can use, too, if the clamp isn't sensitive enough.
Kurt - SF Bay
-
dyarker
- Posts: 1917
- Joined: Fri Aug 22, 2003 1:01 am
- Location: Izmir, Turkiye; from Rochester, NY
- Contact:
?????? Are the alternators going to be okay running with shafts vertical?
I ask because in most vehicles alternators are mounted with shafts horizontal. So I wouldn't think that most alternators have thrust bearings to support weight of rotor.
Other than that question, very impressive!
Cheers,
I ask because in most vehicles alternators are mounted with shafts horizontal. So I wouldn't think that most alternators have thrust bearings to support weight of rotor.
Other than that question, very impressive!
Cheers,
Dale Y
-
dacflyer
- Posts: 4749
- Joined: Fri Feb 08, 2002 1:01 am
- Location: USA / North Carolina / Fayetteville
- Contact:
the alternators should be just fine, as the bearings are pressed onto the shafts, so it should be just fine in a vertical position
now if it was sleeved then there would be a problem,
but typically all alternators have pressed on sealed bearings.
i have had a few set ups with vertical alternators,and have had years of service with no problems.
good luck.
now if it was sleeved then there would be a problem,
but typically all alternators have pressed on sealed bearings.
i have had a few set ups with vertical alternators,and have had years of service with no problems.
good luck.
The vertical mounting scheme is certainly not what Ford intended when they designed these alternators, so it's definitely a concern to certain degree.
The top bearing is sealed on both sides and serves to control thrust play as well. It's not pressed onto the shaft, but it's bushed and cinched with the pulley nut in such a way that there's no slide play between the shaft and the bearing itself.
The weight of the armature mounted vertically creates a down-force it's not set up for (ie - a conic bearing), but I'm hoping the effect is minimal as the armature isn't terribly heavy. I think the bearing will fail much sooner as a result of the belt tension, if it fails at all. Still, I'll keep some spare bearings around just in case.
Dacflyer's experience with vertically mounted alternators is reassuring. Thanks for posting.
The top bearing is sealed on both sides and serves to control thrust play as well. It's not pressed onto the shaft, but it's bushed and cinched with the pulley nut in such a way that there's no slide play between the shaft and the bearing itself.
The weight of the armature mounted vertically creates a down-force it's not set up for (ie - a conic bearing), but I'm hoping the effect is minimal as the armature isn't terribly heavy. I think the bearing will fail much sooner as a result of the belt tension, if it fails at all. Still, I'll keep some spare bearings around just in case.
Dacflyer's experience with vertically mounted alternators is reassuring. Thanks for posting.
Kurt - SF Bay
Who is online
Users browsing this forum: Google [Bot] and 65 guests