Could I add 200 rpm to module signal?

[Yoda439]

Problem: I need to fool engine governor control module into thinking engine is running at 2200 RPM in lieu of the 2000 RPM pre-programmed setting. I need engine to maintain 1800 RPM at 60 hz for whole-house 20KW generator. Reason being this particular Governor control has PIC programmed RPM settings of 1350, 2000 and 2400 RPM. My engine is a Ford 4 cylinder gas LSG4231 with a Ford Dura spark module (white grommet). Got tired of having to hook up to tractor PTO and just opted for this permanent driver engine.

Idea: My idea is if the module pre- programming thinks engine is running at 2200 RPM in lieu of the preset 2000 RPM it will compensate by dropping off the 200 RPM needed to get to 1800 RPM 60hz area where I need to be. Also if there was a trim pot in this circuit I could fine tune this setting even better. I have schematics of original sweeper unit wiring this controller was originally designed for which is a big help in how this unit functions. I also have schematic of how the controller wires to engine module and actuator.

I am a newbie to electronics and my knowledge is limited. I have built variable psu, basic alarms, 555 timer tester, octopus tester among others. I own and love an ESR meter and have old CRT Oscilloscope I am still trying to learn. I read several other post here and came across a 555,4093,4017 decade circuit I think I am looking for to make this work. I am not looking for anyone to build my circuit for me but help me with the vast knowledge I see here. I want to learn how these IC’s function and what they can do. I just need a start in the right direction.Thanks

 

[mneary]

What type of sensor does the governor use? Is it from the ignition or is it independent?

It's not practical to "add" rpms to the governor; more likely you'll end up multiplying its input pulse rate.

What is the pulse rate? If it's straight off the ignition of a 4-stroke 4 cyl engine it would be 3600 pulses per minute (60.0 Hz) at 1800 rpm. To simulate 2000 rpm it needs to produce 4000 pulses per min or 66.6... Hz.

I would use a CD4046, PLL. The VCO would be a nominal 666.7 Hz, and divided by 11 to compare against the governor sensor. The VCO would be divided by 10 to pass through to the governor.

 

[Yoda439]

Thanks for your quick reply:What type of sensor does the governor use? Its from the ignition.The digital governor control module (yellow wire) taps into the Ford Dura-Spark ignition module to obtain RPM Freq. Two wires from this Gov. control go to actuator/servo maintaining rpm. I have the PDF's specs for both the Digital controller and the Actuator/Servo.
What is the pulse rate? I will look up specs for Ford Dura-Spark module and post. I will get specs for the 4046 PLL also.Basically all I want to do is manipulate the return rpm freq. by + 200 RPM. Is this possible? I mean to clock the rpm freq.thus adding this constant error? Thanks
Thanks

 

[mneary]

I repeat that adding a number of pulses, etc. is very difficult. Probably needs a microcomputer.

Multiplying by a ratio of integers is simple and easy. This is why I propose multiplying it by 11/10. The circuit would be simple, accurate, and easy to build.

If you want to add a fixed 200 rpm I can offer no help at all.

 

[Yoda439]

Thanks so much for your patience. I will go with your advise. I will get my bread board out and the 4046 PLL. What else do I need? I have been building up good supply of components.
Also here is some pics and info on this project. I have PDFs also but this page only allows JPEGS etc.. However I could email them to you if need be.

**broken link removed**

 

[mneary]

You need a device that accepts the incoming 60 Hz (probably 12V pulses) and translates it to your logic level. Since we know very little about it I suggest an opto isolator. The signal is low frequency so almost any type will do.

Of course, the 4046, with components to have a center frequency of 667 Hz.
You need chips that can divide by 10 and 11. 4017 will divide by 10. Maybe 4516 for divide by 11. If you can't find a divide by 11 circuit I'll help, but not tonight, it's 1:30AM here. You might want to invert or buffer some signals; it's hard to tell now. Typical inverters and buffers are the 4049 and 4050. Depends on signal polarity, and load resistance.

Finally another opto for the 67 Hz output, to control noise and if necessary change logic levels back to 12V.
---------------
Pdf is allowed, maybe it needs mod approval for new members.

 

[Yoda439]

Here is some schematics/Pics
**broken link removed**

**broken link removed**

Thanks

 

[Roff]

I may be wrong, but it seems to me that if you want the generator to put out 1800 RPM while the control module still sees 2000 RPM, you will need to multiply the frequency by 1.1111..., which is difficult to do
Multiplying by 1.1 will yield an output of 1818 RPM, which is close enough for appliances, but not for clocks. If your clocks running 1% fast is not a problem, then x1.1 should be fine. See the upper scheme in the attached diagram.

It might be better to set the control module to run at 1350 RPM, and use one of the lower schemes in the attached diagram.

 

[tcmtech]

So why cant you just buy an 1800 RPM modual?

I had a frequency matching problem once with an automotive application that involved using a modern computer based engine and transmission control system that was adapted to an older vehicle that used a different low frequency speed sensing circuit.

I just used a frequency to voltage converter IC and converted the variable low frequency signal to a variable DC output. That in turn was sent to a voltage to frequency converter IC that reconverted it to the correct signal for the EEC unit to interpret correctly.
Add a trim pot to the correct point and you have an adjustable fine tune function as well.

Heres the two specs sheets with their suggested circuit layouts.

 

[mneary]

I may be wrong, but it seems to me that if you want the generator to put out 1800 RPM while the control module still sees 2000 RPM, you will need to multiply the frequency by 1.1111..., which is difficult to do

Actually not difficult at all, 1.1111... is 10/9. I guess I screwed up the arithmetic! Thanks for catching that. So you set the VCO to a nominal 600Hz. Divide by 10 for the VCO comparator and divide by 9 for the governor.

Multiplying by 1.1 will yield an output of 1818 RPM, which is close enough for appliances, but not for clocks. If your clocks running 1% fast is not a problem, then x1.1 should be fine. See the upper scheme in the attached diagram.

It might be better to set the control module to run at 1350 RPM, and use one of the lower schemes in the attached diagram.

 

[Roff]

Actually not difficult at all, 1.1111... is 10/9. I guess I screwed up the arithmetic! Thanks for catching that. So you set the VCO to a nominal 600Hz. Divide by 10 for the VCO comparator and divide by 9 for the governor.

Yeah, don't know how I missed that.
Still, dividing by 3 and 4 might be simpler.

 

[mneary]

Here is some schematics/Pics
**broken link removed**
Thanks

They are probably nice pics, but it looks like getting high resolution requires me to purchase prints.

 

[Yoda439]

I may be wrong, but it seems to me that if you want the generator to put out 1800 RPM while the control module still sees 2000 RPM, you will need to multiply the frequency by 1.1111..., which is difficult to do
Multiplying by 1.1 will yield an output of 1818 RPM, which is close enough for appliances, but not for clocks. If your clocks running 1% fast is not a problem, then x1.1 should be fine. See the upper scheme in the attached diagram.

It might be better to set the control module to run at 1350 RPM, and use one of the lower schemes in the attached diagram.

Thanks to all of you for your feedback. This module has three preset speeds.1350,2000 and 2400 RPM. Since I am new at this I just logically assumed it would be less complicated to work off the 2000 RPM setting since it is closer to the 1800 RPM I am after.I thought since all the box cares about is maintaining its preset speed chosen which is monitored by the Freq. (yellow wire). If while set at the 2000 RPM setting if I could convert this right before it enters the digital control to read 2200 RPM the module would do its job and drop off the 200 RPM placing me at the sought after 1800 RPM.
Am I wrong in my thinking here? The one idea of using the Freq. to Volt. converting it into a voltage and then using Volt. to Freq. to convert it back along with a pot to fine tune sounds logical to me. You folks are the experts here and it is over my head but I am willing to build it and mostly learn what I have built and how it works.The math involved as to how to arrive at these desired Freq. is old news to all of you but amazes me.
Sure I can purchase the correct control box for $428 + shipping but maybe I wrongly assumed this could be fun and educational and done simple enough with the right components/IC's and some expert help. I am starting to think I am over my head here and maybe I should go back to building some flashing 555 light thingys. hehe I have my breadboard out and ready to have some fun and the worst I can do is fail and blow up some IC's.BTW I have a Tek. 465M 100 Mhz c.r.t. scope and a BK 3011B Funtion Gen. with digital display.Should I get a freq.counter for this type IC work or do you just use math/caluculators to arrive at the proper freq.I saw a nice freq.counter kit on Ebay for $15 + ship.What do you all recommend.BTW I uploaded some of the pics here also.I am just waiting for the final word on best IC's to order.I think I will just order several on the list just in case and for future fun.Thanks

 

[Yoda439]

They are probably nice pics, but it looks like getting high resolution requires me to purchase prints.

Probably the shirt or coffee cup would be a better choice haha I am gonna set up a blog which will be more useful for this type info.BTW how do I post the PDF's here? I got album set up for pics already on this fourm under my name.BTW I have a slew of resistors already,what range supply of electrolytic caps should I order.. I have good supply of disc.style non-polarity style already.Also should I run this circuit though a 7812 Volt reg.first? Thanks to all of you for your help.Got the boat off Lake Erie and winterized and firewood split so should have more time for some of these fun projects.

 

[mneary]

With a function generator and a scope is enough. If you do it with a PLL the ratio is digital and you just need to check for gross errors. If you use F/V followed by V/F the scope's timing error probably won't matter.

To post a pdf, click 'go advanced' and below the edit window (you'll have to scroll) is 'manage attachments'. Once you get the popup you have the choice of selecting a file on your computer or one on a website. Be sure to click 'upload' when the names are right. It might need to wait for a moderator - I don't know what the rules are for new members.

I would keep electrolytic caps in the 10, 47, 100, 470µF range, at least 16V but preferably 25V. Whatever you can get cheap . If I didn't already have stock, I would be tempted to get Night Fire Electronics "Aluminum Electrolytic Capacitor Axial-Only Kit #3" from their ebay site. (nfceramics). The current listing is item 220241753729. Saves a lot of picking around for just $14.

A voltage reg isn't necessary if you have 5-15V and using CMOS. The 7812 needs 14.5V in to work properly, which isn't a good match for a car's 12-13.8V.

I was lazy Friday and didn't make a diagram for a 10/9 frequency multiplier. Tomorrow?

 

[Roff]

Thanks to all of you for your feedback. This module has three preset speeds.1350,2000 and 2400 RPM. Since I am new at this I just logically assumed it would be less complicated to work off the 2000 RPM setting since it is closer to the 1800 RPM I am after.I thought since all the box cares about is maintaining its preset speed chosen which is monitored by the Freq. (yellow wire). If while set at the 2000 RPM setting if I could convert this right before it enters the digital control to read 2200 RPM the module would do its job and drop off the 200 RPM placing me at the sought after 1800 RPM.

I think you are correct. What threw me off was the 2200 RPM that you mentioned. That would never appear, because the feedback loop would keep the input to the controller at 2000, and the output of the generator at 1800. I think you knew that.
What mneary is showing you is the most stable way of achieving this (although it is achieved by frequency multiplication instead of addition). The F/V/F method (which is also multiplication instead of addition) has the potential to drift enough over several hours to cause your clocks to need to be reset if you are fussy about time.

 

[tcmtech]

In most backup power situations your more concerned about how well your generator system can cope with its load. Not how accurate your digital clocks are.

As far as typical engine governing systems the F/V/F system is simple to build, easily recalibratable, and more than stable enough to serve its function if properly built and will likely have no worse RPM drift or inaccuracy than that of any standard mechanical governor system that is on the tractor that powered the PTO generator any way.

Any portable engine driven generator system has a fair amount of natural RPM drift. Its just part of the design. They have a small dead band in order to keep them from hunting while under load. I run my gen sets at around 63 Hz no load and typically get around a 57 Hz output at the full rated load. The average loading still works out to around 60 Hz over time anyway.

If keeping proper time or the difficulty of resetting some clocks is that bad I suggest buying some replacement atomic clocks instead!

 

[mneary]

Attached is a tested schematic of the 10/9 (1.1111...) multiplier. I/O may require buffering, depending on the signals to be interfaced.

 

[Yoda439]

Yeah, don't know how I missed that.
Still, dividing by 3 and 4 might be simpler.

Was wondering if you divided by 10/9 working off the 2000 or 3/4 working off the 1350 RPM setting what is this difference? Would one over the other be more accurate,take less components? I don't know and am just asking why one is better or why one would be worst? On my generator when RPM is manually set(not governed) at 1800 RPM putting out 220V at 60 Hz all is fine. However when a big load is placed on it like my 1-1/2 HP 220V well pump which is 320 Feet deep it draws 14 amps just to start and about 7 amps to run. With no governor generator slows down, the house lights dim (bad) because the engine is not governed at 1800 RPM.If I quickly manually adjust it back to 1800 at 60 Hz all is fine until the (load) well pump kicks off and then I it now revs over 1800 and over 60 Hz (bad). Also am I wrong in the way I am approaching this problem? I need someone to clarify my thinking that this control box has programming already with three speed sets. I need 1800 with maybe an adjustable pot for variation. So on the computation of the divide by 10/9 should not the answer be 2000 converted to 2200 RPM then when the control software sees this it will compare and drop off 200 RPM thus placing me at 1800 RPM.Or the divide by 3/4 based working up from the 1350 RPM setting. Should it not deduct 450 RPM placing RPM now at 950 as seen by the control.Then the control would add 450 RPM putting the governor at 1800? What am I missing? I am learning several things here and appreciate all input since I am inexperienced at these thinking processes. Thanks

 

[Yoda439]

Sorry I posted this last before I read page 2 so nobody thinks I am goofy.Thanks