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RPM controls the PWM ?? I have an idea..
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daddymikey1975 Offline
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Post: #1
RPM controls the PWM ?? I have an idea..
I'm certainly no electrical engineer but I would LOVE for someone to try a few tests as I don't have a PWM... most engines DO have a Camshaft Position sensor, or a Tach signal, or if one was unable to find a tach signal, the the UN-common wire at a fuel injector would suffice... here's where I'm taking this...

Would it be possible to use the Fuel injector pulse (also controlled by the computer's PWM for fuel delivery) or use the Tach signal or the Cam position sensor to produce a voltage, or a pulse that can be fed into the input of our PWM's to control the Duty cycle automatically ?? I'm still not understanding the individual parts of the PWM circuit, however I do know what one is, and what it's for... I DO know that the tach signal is pulsing DC voltage, but if you measure it with your meter on DC it's USUALLY between 1 and 4 volts depending on engine RPM.. this varying voltage COULD POSSIBLY be the input voltage in place of the rheostat to control the duty cycle...

anyone with a PWM think they'd like to undertake this challenge?? if I had one I'd try it in a minute...

anyone else think it could work ? we'd need a high impedance circuit so as not to affect the vehicle operation, but i think we could 'read' that varying voltage and use it to our advantage instead of a throttle linkage connected to a var. resistor...

(OR what about using the TPS sensor that's already there?? parallelling off of it?? just another idea for throttle position..)

anyhow, thanks for the advice/replies.

mike
10-10-2008 01:45 PM
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benny Offline
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Post: #2
RE: RPM controls the PWM ?? I have an idea..
daddymikey1975 Wrote:I'm certainly no electrical engineer but I would LOVE for someone to try a few tests as I don't have a PWM... most engines DO have a Camshaft Position sensor, or a Tach signal, or if one was unable to find a tach signal, the the UN-common wire at a fuel injector would suffice... here's where I'm taking this...

Would it be possible to use the Fuel injector pulse (also controlled by the computer's PWM for fuel delivery) or use the Tach signal or the Cam position sensor to produce a voltage, or a pulse that can be fed into the input of our PWM's to control the Duty cycle automatically ?? I'm still not understanding the individual parts of the PWM circuit, however I do know what one is, and what it's for... I DO know that the tach signal is pulsing DC voltage, but if you measure it with your meter on DC it's USUALLY between 1 and 4 volts depending on engine RPM.. this varying voltage COULD POSSIBLY be the input voltage in place of the rheostat to control the duty cycle...

anyone with a PWM think they'd like to undertake this challenge?? if I had one I'd try it in a minute...

anyone else think it could work ? we'd need a high impedance circuit so as not to affect the vehicle operation, but i think we could 'read' that varying voltage and use it to our advantage instead of a throttle linkage connected to a var. resistor...

(OR what about using the TPS sensor that's already there?? parallelling off of it?? just another idea for throttle position..)

anyhow, thanks for the advice/replies.

mike

Regarding the pulse for fuel injectors, this can vary for different car makes, and different fuel types, petrol (gas) or diesel. Some use a single pulse for all injectors, Some injector systems are pulsed in individually, some in pairs, and some in groups of three (6 cylinder engines) and some engines pulse all injectors simultaneously. Depending on make you could adjust the pulse count to suit and set pwm accordingly.
I doubt very much whether rapid acceleration, and deceleration, as in stop/start driving would make for accurate tracking with HHO/gas ratio with changing RPM. There always seems to be a delay in change of rate of HHO production when PWM is adjusted.This is why most users aim for a ball park setpoint, often referred to as the sweet point, when setting up PWM, EFIE etc, where there might be different preferred setpoints for town or highway driving.
It would be possible to set up a compromise/predictive algorithm if a processor or microcontroller were used to oversee this method of varying HHO with RPM, and control PWM output, but even this would never be 100% spot on all of the time.

Regarding reading from high impedance sensor circuits, it is easy to set up a high input impedance buffer using an op-amp configured as voltage follower. This typically draws micro-amps from the circuit being monitored.

Note that you can use a pulse train, applied via a resistor to a capacitor to generate a varying voltage, which you theoretically could use to drive your pwm. However, bear in mind what I mentioned previously regarding apparent lag in rate of change in HHO production.
(This post was last modified: 10-10-2008 02:39 PM by benny.)
10-10-2008 02:37 PM
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daddymikey1975 Offline
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Post: #3
RE: RPM controls the PWM ?? I have an idea..
benny Wrote:Note that you can use a pulse train, applied via a resistor to a capacitor to generate a varying voltage, which you theoretically could use to drive your pwm. However, bear in mind what I mentioned previously regarding apparent lag in rate of change in HHO production.

I understand what you mean that there's a lag in rate change when the PWM is adjusted, however if you were to use a tach signal as your controlling signal, you could definitely compensate for differences that are quite wide, such as idling or cruising at highway speeds... not necessarily 'exactly' following engine RPM's... or have a preset duty cycle at idle (whatever the idle voltage is as measured from a coil pack signal, or tach signal, and then have a bit of an increased duty cycle for cruising at highway speeds.

I install remote starts for a living and i completely understand what you mean by the injectors being pulsed at different rates/times/durations and in pairs, or not depending on engine. We usually go directly to a coil pack for a tach signal, and this gives the best result when trying to find engine RPM as it's the same cylinder firing for the same duration at the same time every revolution, it just fires faster when RPM's increase so this would be an ideal sourse for the controlling circuit of the PWM... and even if there's a bit of a lag in HHO production after an adjustment is made, the ECU would be compensating at any rate for the acceleration, but by the time you're cruising along, your HHO should be up to snuff..

sorry for the long read.
Thanks for the insight.

hope this helps as well
(i'm still willing to experiment if anyone has spare parts laying around)

mike
10-10-2008 02:59 PM
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alpha-dog Offline
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Post: #4
RE: RPM controls the PWM ?? I have an idea..
daddymikey1975 Wrote:
benny Wrote:Note that you can use a pulse train, applied via a resistor to a capacitor to generate a varying voltage, which you theoretically could use to drive your pwm. However, bear in mind what I mentioned previously regarding apparent lag in rate of change in HHO production.

I understand what you mean that there's a lag in rate change when the PWM is adjusted, however if you were to use a tach signal as your controlling signal, you could definitely compensate for differences that are quite wide, such as idling or cruising at highway speeds... not necessarily 'exactly' following engine RPM's... or have a preset duty cycle at idle (whatever the idle voltage is as measured from a coil pack signal, or tach signal, and then have a bit of an increased duty cycle for cruising at highway speeds.

I install remote starts for a living and i completely understand what you mean by the injectors being pulsed at different rates/times/durations and in pairs, or not depending on engine. We usually go directly to a coil pack for a tach signal, and this gives the best result when trying to find engine RPM as it's the same cylinder firing for the same duration at the same time every revolution, it just fires faster when RPM's increase so this would be an ideal sourse for the controlling circuit of the PWM... and even if there's a bit of a lag in HHO production after an adjustment is made, the ECU would be compensating at any rate for the acceleration, but by the time you're cruising along, your HHO should be up to snuff..

sorry for the long read.
Thanks for the insight.

hope this helps as well
(i'm still willing to experiment if anyone has spare parts laying around)

mike

I'm going to ask some of my engineering friends here about this because I also believe rpm would be a great way to control HHO output. After all you don't need maximum production of hho at idle. I'm thinking that useing engine rpm's might provide a linear stepping up of HHO production.
Russ
10-14-2008 05:10 PM
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alpha-dog Offline
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Post: #5
RE: RPM controls the PWM ?? I have an idea..
If you remove U1a and U1B of the ZeroFossilFuel PWM and go into pin 9 of U1C with a dual-flipflop (7474) , maybe two of them from your rpm output you might knock the freq. down enough to work and still have current limiting.
Russ
10-14-2008 05:39 PM
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daddymikey1975 Offline
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Post: #6
RE: RPM controls the PWM ?? I have an idea..
Alpha dog, that sounds promising.. I have an additional scenario as well... (now we're getting complicated) lol..

if we could control the duty cycle via RPM that would be sweet.. but what if we were able to incorporate a feedback circuit as well?

here's my idea (and i was just brainstorming.. here's my tangent)
1. I was going to experiment with an O2 extender once i put my cell in the car. There's a problem with doing this though. The problem is if i don't have my generator producing, my engine will be running too lean. To solve this i was going to have a muffler shop weld in another bung for a second 02 sensor that i can switch to so the computer will see the proper O2 level if the generator is not running. (kinda like the adjustment or not mode of an efie)
2. I then figured, why not just get an efie for that because it can be shut off if the gen. is not running.. simple enough, but what about that second bung idea??
3. If we were to get a second O2 sensor in the stream and connect it to our PWM only, how could we incorporate a feedback circuit to adjust our PWM semi-automatically based on our sweet spot... we could still dial in the sweet spot with a trim pot.. but then the secondary O2 sensor would maintain this...??

does it sound do-able? logical? just a brainstorm...

hope this helps.
mike
10-15-2008 01:27 AM
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alpha-dog Offline
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Post: #7
RE: RPM controls the PWM ?? I have an idea..
daddymikey1975 Wrote:Alpha dog, that sounds promising.. I have an additional scenario as well... (now we're getting complicated) lol..

if we could control the duty cycle via RPM that would be sweet.. but what if we were able to incorporate a feedback circuit as well?

here's my idea (and i was just brainstorming.. here's my tangent)
1. I was going to experiment with an O2 extender once i put my cell in the car. There's a problem with doing this though. The problem is if i don't have my generator producing, my engine will be running too lean. To solve this i was going to have a muffler shop weld in another bung for a second 02 sensor that i can switch to so the computer will see the proper O2 level if the generator is not running. (kinda like the adjustment or not mode of an efie)
2. I then figured, why not just get an efie for that because it can be shut off if the gen. is not running.. simple enough, but what about that second bung idea??
3. If we were to get a second O2 sensor in the stream and connect it to our PWM only, how could we incorporate a feedback circuit to adjust our PWM semi-automatically based on our sweet spot... we could still dial in the sweet spot with a trim pot.. but then the secondary O2 sensor would maintain this...??

does it sound do-able? logical? just a brainstorm...

hope this helps.
mike

The current limiting PWM design by ZFF could be used to address this.
I was also thinking that maybe coil some solid strand wire around one of the spark plug wires ( if thats possible ) grounding one end and using the other might provide an rpm signal.
Russ
10-17-2008 12:25 PM
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daddymikey1975 Offline
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Post: #8
RE: RPM controls the PWM ?? I have an idea..
alpha dog, I have access to tech info for any car imaginable.. I install remote starts for a living (have for 15 years)

If you (or any member for that matte) needs ignition switch, tach, or other info that's available to me i'd be more than happy to share.

the tach signal that I have available, would DEF. give you RPM ... for example on my van 99 dodge Caravan here's all the info that I have avail:


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1999 Dodge Caravan DirectWire 2.0 Vehicle Information


All Products


Item Wire Color Polarity Wire Location
12 Volts red + ignition harness
Second 12 Volts
Starter yellow + ignition harness
Second Starter
Ignition blue + ignition harness
Second Ignition black/orange + ignition harness
Third Ignition
Accessory black/white + ignition harness
Not required for remote start.

Second Accessory
Third Accessory
Keysense
Data Bus
Can Bus High
Can Bus Low
Can Bus Sw
Power Lock white/green left plug at bottom of fuse
Use relays and set up for negative trigger. Place a 4020 ohm resistor inline on the lock output, and a 665 ohm resistor inline on the unlock output. If you do not have a factory security system use a 1500 ohm for lock and a 250 ohm for unlock.

Power Unlock same wire box under cover (1 of 3)
Lock Motor brown
The door lock motor wires are located in the top left plug at the relay/fuse box under the drivers side of the dash.

Driver Unlock Motor black/pink
The door lock motor wires are located in the top left plug at the relay/fuse box under the drivers side of the dash.

Passenger Unlock Motor violet/white
The door lock motor wires are located in the top left plug at the relay/fuse box under the drivers side of the dash.

Parking Lights (-) grn/wht or grn/red at light switch
If the van has autolamps, see DirectFax document 1080.

Parking Lights (+) do NOT use
Hazards
Turn Signal (Left)
Turn Signal (Right)
Headlight lt. green/orange - at light switch
AutoLights
Reverse Light
Left Front Door Trigger brown/lt. green - dome light on/off switch
Right Front Door Trigger
Left Rear Door Trigger
Right Rear Door Trigger
Dome Supervision brown/white - dome light on/off switch
Trunk/Hatch Pin tied in with doors
Rear Glass Pin
Hood Pin do not use
Trunk/Hatch Release
Trunk Release Motor
Fuel Door Release
Power Sliding Door (Left)
Power Sliding Door (Right)
Factory Alarm Arm arms with lock
Factory Alarm Disarm disarms with unlock
Disarm No Unlock see DirectFax document 1081
Trunk Alarm Shunt
Tachometer gray or gray/red ignition coil
Wait to Start
Neutral Safety
Clutch Pedal
Fuel Pump
Rear Defroster
Mirror Defroster
Left Front Heated Seat
Right Front Heated Seat
Speed Sense
Brake Wire white/tan + brake switch
Parking Brake
Horn Trigger gray/orange - top right plug of fuse box
Wipers pink/purple - steering column
Left Front Window (Up/Down) lt. green - white A drivers door switch
Right Front Window (Up/Down) brown - purple A drivers kick panel
Left Rear Window (Up/Down) dk. blue - red A drivers kick panel
Right Rear Window (Up/Down) gray - dk. green A drivers kick panel
Sun Roof (Open/Close)
Sun Roof (Limit/Close)
Memory Seat 1
Memory Seat 2
Memory Seat 3
Radio 12V
Radio Ground
Radio Ignition
Radio Illumination
Factory Amp Turn-on
Power Antenna
Left Front Speaker (+/-)
Right Front Speaker (+/-)
Left Rear Speaker (+/-)
Right Rear Speaker (+/-)
Center Channel (+/-)
Subwoofer (+/-)
Aux. Audio Input Left (+/-)
Aux. Audio Input Right (+/-)
RSE Video (+/-)
RSE Audio Left (+/-)
RSE Audio Right (+/-)
Satellite Radio 12 Volts
Satellite Radio Ground
Satellite Radio Ignition
Satellite Radio Antenna
Satellite Audio Left (+/-)
Satellite Audio Right (+/-)
Item Size Depth Location
Headunit
Left Front Speaker
Left Front Tweeter
Right Front Speaker
Right Front Tweeter
Left Rear Speaker
Left Rear Tweeter
Right Rear Speaker
Right Rear Tweeter
Center Channel
Subwoofer
Left Front Headrest
Right Front Headrest
Left Rear Headrest
Right Rear Headrest
Satellite Radio Tuner



Smart Starter Kill Relay


Relay Type:
Part #:
OE Relay Part #:
Location:
n/a
n/a


n/a


Notes:


n/a


Alternate Part Notes:


n/a








Interface Modules


SKU Module Description Upgradeable Keys Required for Programming Keys Required for Operation
The are no interface modules listed for this vehicle.




© 2007 Directed Electronics. All Rights Reserved.
DirectWire and its vehicle information are for the sole use of authorized Directed Electronics personnel and it's participating dealers and distributors. The information contained on these pages may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited.
10-18-2008 03:00 AM
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mobilehydricity Offline
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Post: #9
RE: RPM controls the PWM ?? I have an idea..
alpha-dog Wrote:
daddymikey1975 Wrote:Alpha dog, that sounds promising.. I have an additional scenario as well... (now we're getting complicated) lol..

if we could control the duty cycle via RPM that would be sweet.. but what if we were able to incorporate a feedback circuit as well?

here's my idea (and i was just brainstorming.. here's my tangent)
1. I was going to experiment with an O2 extender once i put my cell in the car. There's a problem with doing this though. The problem is if i don't have my generator producing, my engine will be running too lean. To solve this i was going to have a muffler shop weld in another bung for a second 02 sensor that i can switch to so the computer will see the proper O2 level if the generator is not running. (kinda like the adjustment or not mode of an efie)
2. I then figured, why not just get an efie for that because it can be shut off if the gen. is not running.. simple enough, but what about that second bung idea??
3. If we were to get a second O2 sensor in the stream and connect it to our PWM only, how could we incorporate a feedback circuit to adjust our PWM semi-automatically based on our sweet spot... we could still dial in the sweet spot with a trim pot.. but then the secondary O2 sensor would maintain this...??

does it sound do-able? logical? just a brainstorm...

hope this helps.
mike

The current limiting PWM design by ZFF could be used to address this.
I was also thinking that maybe coil some solid strand wire around one of the spark plug wires ( if thats possible ) grounding one end and using the other might provide an rpm signal.
Russ

HEY! I treid that about 4 years ago.. Seemed like a good idea to get a pulse..I used a fast switching diode on one end of the coil of wire around the spark plug wire and the other slightly above ground. Couldn't get enough output from the sampling method to do any good. Decided to go with an earlier idea ,of placing magnets on the transaxle and using a magnetic latching switch to sense when the magnets passed by the switch. using a 5 volt regulator and a zener diode ..passing low voltage threw :cool:the switch, now gave me an on /off sample that changed with the acceleration of the car. a register, that can be stacked. This method was used in early , after market speed control devices. If available , I use the tach out pulse. Included is a schm. of an earlier circuit that is a standalone unit .Hope it helps you. MIKE
10-21-2008 09:55 AM
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daddymikey1975 Offline
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Post: #10
RE: RPM controls the PWM ?? I have an idea..
mobilehydricity Wrote:If available , I use the tach out pulse. Included is a schm. of an earlier circuit that is a standalone unit .Hope it helps you. MIKE

That's what I'm referring to is the tach pulse...and use this to control duty cycle so that at idle, we're not making max production, while sacrificing 'some' at highway speeds... we could also use the speed signal from the transmission to the ECU if you want something more relative to speed.
Again, I have access to this info as well specifically wire color, location, and pulses per mile. This could be used to control duty cycle to ramp up production as speed increases and 'top out' at the sweet spot for your motor at a given speed.

For example some newer GM vehicles have a green/white wire behind the radio that gives you 4000 pulses per mile. The radio needs this pulse info for their speed control volume feature. If needed, I can also tell you where at the ECU this wire can be found as well, and for other cars.

No need for magnets on the driveshaft. Although, I've used that method for getting a speed signal on some older vehicles while installing cruise control.

I have some GREAT access to good information if anyone wants to try to incorporate it and see if it works. I'm just not an electrical engineer and wouldn't be able to incorporate this idea into a working circuit.

mike
10-22-2008 04:04 AM
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