After a few weeks of testing and various setbacks I feel pretty good about the basic circuit. I wanted to make this thing Scaleable. Meaning, if you want an audio alarm on Water Temp, or whatever, or you just want lights, it is all customizable. The document has been started here:
But there is a lot I could use help with. You do not have to be an electronics genius to participate. Some of this has to do with placement in the truck, which Heads-Up's are important to you, etc.
Then there are questions I have not resolved like: Concerning the Water Temp Sensor... We can't move what is already there because our vintage gauges need that mechanical signal, so where do we put a second sensor (has to be in water to work)?
Is a fuel gauge (gas tank going empty) something we could use and if so, what can we use for a sensor for that?
I am sure more questions will arise as the discussion develops. Check out the article and let's discuss your ideas here. Thanks!
Thanks, first problem that we should address is something I ran across yesterday. I was changing over the bulbs to LED thinking they would behave the same in the circuit. Wrrrrrong!!
So, if you have a three wire 10SI type Alternator, the incandescent dash light bulb works but to get the bulb to go clear out (not dim) you have to add a 1N4005 diode. Since the LED IS a diode, it does not go out sufficiently to cause my relay to trip. So, it's either back to an incandescent Alternator Warning Light, or maybe someone here has enough knowledge to overcome the LED problem?
The differential voltage that drives the incandescent light will not drive the LED. The LED is polarized, volts will only go 1 way. That light won't care what the direction is. It gets more complex than you think. I would use an op-amp to sense a differential and drive the LED with that. Not as simple as plugging in the light. Try looking up differential amp for a start.
Actually, to be correct, it is Current that "flows" not Volts, but it makes sense to more folks when you get to "direction" for the + to flow to the - . Hens the Volts reference above.
I am getting the LED warning light issue worked out. I think I have it. It's better with everyone going to LED to make sure parts are available years from now, so I want to make that happen.
I am working on the water temperature alarm and the best place I can think of to add an electrical sensor while keeping the mechanical one for our gauge set is to put a Tee connection at the rear engine drain cock. The sensor has to be in water and I like the idea of being able to still use that for the drain. If we can have the best of both worlds, let's do it! Suggestions are always appreciated. Now I need to find a normally closed alarm sensor in 1/4" NPT!
Now we have a way to see the alarm lights without it looking Tacky. Right? If there is something I missed in the design of this, please let me know. Always interested in making it better.
Has anyone else noticed how slow shipping has gotten these days? Anyway, finally got in the parts I needed to locate the Water Temperature Sensor. If it works correctly we will have a nice out of the way place to put our sensor. If not, back to the drawing board. Once more parts come in, I will begin testing.
Tested the idea of using the rear engine drain port to add a water temp sensor. I installed the main temperature sensor in the rear drain port, and the new warning sensor in the Head. This way I could tell for certain what we were dealing with. It was interesting...
The rear drain will NOT be a suitable place to put a second sensor. I was uncertain, but now I know for sure what happens. Turns out, the temperature never reaches the 180 degrees the sensor reads when it's in the Head. It reads 30 degrees less. The reason for this I think is due to the 1/4 inch outlet and the fan blowing over it with very limited water circulation. The test ran for 20 minutes at 2000 rpm, so it was long enough. So that idea is out the window. Our warning sensor needs to read 230 degrees before it sounds off, so if we can't get 150 out of it, fuggetaboutit!
The next attempt and one that sounds more promising is the top heater hose port. It's at the lower thermostat housing. When using an IR Thermometer during the test today, I was getting 180 degrees (the same as the radiator hoses) in that location. It will work from a physical standpoint because you can still put your heater valve just after it. So, in the next few days, I will have the results of that location. More to come...
Ron Francis wiring makes a electric fan controller (AR-67) that uses a thermister temp sensor that is soldered into a bolt lug. Install the sensor via one of the T-stat housing bolts, set the controller at 230* and connect the warning light to the fan on relay contact and you're done. I have this set up to control my electric fan in my '56, works great!
This controller also has a A/C input relay that will run the fan whenever the A/C is on, so you could connect the oil sensor to that input and when it trips it will light the same warning light.
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
I hadn't even thought of a Thermistor. Interesting. No worries about finding a place for a conventional temp sensor. The price has to be significantly lower to make it work, but it's a great avenue I haven't gone down yet.
and the fun part begins! Thanks again Mike! If you get them from Mouser or somewhere like it, they are about $5 each. I just hope I am smart enough to figure out how to design a circuit for them.
Someone I was talking to today said I shouldn't abandon putting it in the water stream, but to not worry about what is out there for sale limiting me. He said you can take a brass plug of ANY NPT size, drill a hole, fit the Thermistor in the hole and fill the hole with JB Weld. The Thermistor is very small so size isn't an issue. Anyone have comments on doing that? These Thermistors survive open flame so the only drawback I could see would be on the other end where the wires come out. Then there is the whole can of worms concerning making a circuit that reads ohm values and triggers my relay at a certain value. Thanks again Mike! LOL!
Lots of thermisters have been engineered into building temperature controls (thermostats). Contact Kele at http://www.kele.com/ and see if they have a circuit board that will work for you. They have a great engineering staff and are very knowledgable. No sense re-inventing the wheel...
You would need to encapslate the thermister and wires that passes through the brass fitting to make them water tight.
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
This looks promising. I can even wire it for normally closed which fits with my current circuit design. Now all I have to do is wait for the boat. I am thinking if you can wire this to turn on a fan at a certain degree point Plus or Minus 2 degrees, then there is no reason it wouldn't work for an over temp alarm. I designed it so it only works when the engine is running, so this may be the ticket. Wait and see!
I will be thoroughly testing it when it arrives. Problem is we will be wondering about it for about a month since that is how long it takes to get stuff from them.
This is the reply I got from our Thai friend about the temp differential when I asked. Of course when it gets here that will be thoroughly tested...
"Yes, you can wire at NC, the board has both NO and NC. It is analog board, it has no band gap, example : you set at 50'C, > 50 'C relay close, < 50'C relay open. You have to adjust with the know temperature by thermometer."
Yeah, I like doing everything the hard way apparently. Today I tested the idea of using the Thermostat 1/2" NPT port that goes to the heater with my bi-metal 230 degree switch. Any time you do that, the fan's airstream running across the new fittings cause things to cool down too fast. I think at least I was able to prove once and for all that using the engines water stream to solve the problem isn't going to work. If it weren't for the mechanical gauge needing the Head Port, this wouldnt be an issue, but I feel very good about our next Idea... using a Lug Type Thermistor and associated circuit. Just another wait and see away from success I think. The site is updated to include the last test failure.
I found this fun project on the internet to maybe get people more excited about fixing these small problems using electronic theory. It fit in with the narrative, so I added it to the conversation here:
It's a cheap, fun project that does everything we want for the Water Temp portion. I am keeping myself busy until that shipment from Thailand arrives with the other circuit.
I finally got the circuit in from Thailand yesterday. About three weeks to get stuff from them. A person just needs to have patience which is something I have been saying for three weeks! Anyway, to reiterate what this is all about..
The circuit is very similar to the Ron Francis offering Mike mentioned earlier which uses a thermal resistor to detect temperature as opposed to finding a place in the water jacket to put a sensor. As it comes from Thailand, the thermistor could have a larger lug to bolt it down to the Thermostat Housing, which is my idea for where it could go. It is useable as is, but the lug housing could be larger.
I talked with Alain Stas, an engineer from Brussels, Belgium who works for Vishay Electronics and he spent enough time with me to understand Thermistors. The ones they suggest are here:
These radial lead devices can be housed inside of a tin lug housing and then high temp silcon to hold them down to the lug housing. Then, the two leads are connected to a box inside the cab. The Water OverTemp portion of the circuit is basically just this small board that controls a relay that energizes when the lug temperature reaches a certain point. Energizing the relay will control a Piezo Buzzer and an LED to inform the driver of the Overheat condition.
The nice part about this little circuit is, it also can control an electric fan if you so choose. The temperature is adjustable from 120F to 240F via a small pot on the circuit board. The Thermistor is OEM standard equipment on some new vehicles so the technology is widely accepted as well. At this point I have everything I need to make the first prototype for Oil Pressure/Water Temp and Charging. If anyone has any ideas on what else a warning circuit should cover, let me know.
What a journey this has been! After testing all of the components that make up this system, everything is working correctly and reliably. I was able to go back to a 5 pin relay since the Water Temp Circuit has its own on-board relay.
The system is adaptable to suit those who want warning lights, or those who just want sound. I updated the article but there is more to be corrected and updated in the coming days.
I would love to hear from some of you enthusiasts about the idea of using a lower amperage rated relay to drive a higher amperage rated one. I found a very small (1.25" wide, 1.5 inches long) SIX DOLLAR circuit board that senses temperature, once it reaches the adjustable threshold, engages the 10 amp relay and whatever is connected to the relay is activated. VERY cool.
However, I was talking to SPAL this week and their 16 inch fan requires a 40 amp (surge) relay and then a 30 amp slo-blo fuse to make it work properly. You would think maybe the aforementioned circuit would be insufficient. However, what if you use that little $6 circuit and drive a standard Bosch style 5 pin 40 amp relay? So, you have a total of $10 into the parts to drive your electric fan system. Anyone have any thoughts on doing this?
Good. I wasn't sure but I don't see any reason why not. The driver is the coil, not the relay contacts, so that's great to get that confirmed. Thanks again Mike!
Are you going to market the complete system once you have all the kinks worked out? If I try to follow along and build one of these myself, I guarantee my truck is going up in flames! :-)
The most important thing to me and what I do first is get the website completely accurate for the guys who want to do it themselves. Then I order more parts and put it in the Farm-It-Out section. I like to have two sources for the parts and until a few days ago I only had one. Now I have three! One of them is making the circuit board from scratch. I may be a month or so away. Testing is complete and it's working perfectly. What a ride!
Larry, that's why I use a test engine on a stand with fire extinguishers in reach! I can relate!
Things got a bit delayed because I wanted to understand completely the circuits that are available, then determine which one to use. Turns out the ready made circuits that are out there are not to my liking. There are two finalists and the first one uses non-automotive thermistor and low ohm values that lead to more failures over time. The other one uses the proper values, but still non-automotive thermistor. Then, to top it off, it is not expandable. I want to add a few things to my circuit, so this means re-learning everything I forgot about electronics years ago. It has been a lot of fun and I am really getting into it.
The circuit I am designing from scratch uses 20 amp relays, automotive grade thermistor, a dual IC Comparator that gives me a second Comparator for expansion, and feedback/hysteresis protection. This route enables me to add the last feature I will include in the Basic system, Low Fuel Warning. So the Basic system will have a Charging System Light, Oil Pressure Light/Audible, Water Temperature Light/Audible, and Low Fuel Warning Light. I will offer it customized for each person's desires. Of course all of the plans to make it yourself will be available first.
The rest of it is pretty much complete, but the low fuel warning is in the works now. It will include the ability for the user to adjust where they want to see a low fuel warning. Since it uses the fuel sender, we will be able to adjust it anywhere from almost full to less than empty! It's a bit tricky working with low ohm values like the fuel sender (0-30 ohms), but this has been a real education and something I really enjoy doing. Thanks to everyone who has been encouraging, and to those for actively helping. It's coming soon, but I want to get this right.
After spending a lot of time researching, getting help from the likes of our very own Steve_H, listening carefully to others here and other specialty sites, then re-learning my basic electronics, I now have a very stable circuit that does the following:
1) Acts as an Alternator Charging System warning - On Ignition ON, the White LED comes on, on engine start stays on until 650 RPM is reached, then goes out because the Alternator is working properly. If the light ever comes on while the engine is running, there is a Charging System malfunction.
2) Oil Pressure Warning - At Ignition ON, the Red LED stays off due to the bias placed on the relay by the Alternators Warning Circuit. At Engine on, Oil Pressure rises above 6PSI so fast the alarm never goes off and stays off. The only time you see a Red LED and hear the 95dB Piezo Alarm is with Engine Running and Oil Pressure is below 6PSI.
3) Water Temperature Warning - At Ignition ON clear through normal engine operation, you never even know you have a warning. The only time the Blue LED and 95dB Piezo goes off is when Water Temperature reaches 220 degrees. This number is fully adjustable from Ambient to 257 degrees. Since this is a circuit that you would not even know if a wire was broken to the sensor thermistor, I incorporated a Supervisor Circuit that monitors to ensure all wires are connected properly. If not, an Amber LED mounted to the box itself warns you that there is a system fault.
4) Low Fuel Warning - This circuit has one wire that hooks to the fuel sending unit and monitors the level in your tank. When the sender tells the circuit you have low fuel, the Amber LED warns you to get more fuel. This is adjustable from Empty to Half Full. This makes sense because some folks live 1 gallon away from a gas station, others live 20 miles or more away. This circuit is totally independent from the gas gauge.
Once the individual circuits were prototyped and tested, it was necessary to put them together in one larger circuit. This was all done from scratch using Proto-Breadboards and lots of small hookup wire. Its not pretty, but a necessary step. Once it was thoroughly tested using the test engine and Start Kart, I am now ready to learn how to use a new program called DipTrace. This program takes your schematic diagram and turns it into a Printed Circuit Board file. Just like Draftsight for drawing out Metal for Laser Cutting, this program configures your schematic so that the circuit is designed the most efficiently, then with PC Board Printer technology, Printed Circuit Boards are made. With the learning curve, etc, I am hoping for completed boards in about a month.
Glad you stuck with this one. Nice to learn a few new tricks. The process has not changed much since I did my first "concept to product" in 1968. University was good to me. We used a photo process that required lots of chemicals and time. Printing..well that almost seems like cheating. PWB(printed wire board) indeed.
Things have sure changed since I was making memory upgrades for the original Atari 800 computer in 1979. We had nasty chemicals and copper boards with etching, etc. Radio Shack was your friend! Here is how it is done now:
No more Archer Etchant! What's more is it takes your schematic diagram, and with a few tweaks allows you to go from the schematic to the PCB. It took me about three days to learn this software, so that means anyone can do it. I am hoping to have the boards in my hands within a month, maybe sooner!
Thanks for the kind words Steve! This one is getting interest from some very interesting places.
Well, I got the Printed Circuit Boards back from Bay Area Circuits. I have been very anxious to get them back and see what stupid thing I did because it is my very first experience with a professional software program that does all of the work for you. Here is what I got back from Bay Area Circuits...
These kinds of projects never go perfect the first time, especially for me. But not to be deterred, I just make Lemonade and move on.
The boards were wired correctly per my schematic, so that wasn't it. I used a different LED for testing that was less sensitive so when I put the correct ones in, the Water Temp light was dim and got brighter closer to the set threshold. I found my mistake and fixed the schematic to reflect the proper route. Best to just wire the piezo to the LED so they both get the same signal at the same time. Fixed.
Then, I had not really thought enough about how to attach the long wires that go to the sensors and the LEDs to the circuit board. The screw type terminals are not good for automotive use because they can loosen with vibration. So plan B was to solder everything down. Sounded feasible so that was how these boards were configured. In just a few days of testing, it became obvious that Plan B wasn't going to work. Stranded Hookup wire breaks at the solder joint too easily. I used to know that!
Plan C is to use soldered in Headers. Two pin ones for the LEDs and a 12 pin one for the main connector. Then, crimp on pins are used that lock into place when pushed in. We used hundreds of different cannon plugs, headers, etc with the same type of connections on C-130's, H3's, H53's, Hueys, and T-39s in the Air Force, so I know that vibration is NOT going to be a problem.
This is just one of the steps that are required when you do something like this mostly by yourself. Had I had an engineering team assembled, it would have gone smoother. New boards are on order, the connectors and everything else is already here, and I am anxiously awaiting the new boards.
That said, for months now I have had my prototype hooked up to my test engine and Start Kart. I find myself looking at the Charging LED to make sure I have the engine revved enough to charge the battery and feel just a little better knowing that if for some reason my oil pressure or water temp goes south, I will hear about it right away. I will be adding to my Start Kart document to add this feature as well. Update in another 10 days or so when the new boards get here.
So it's been at least 6 months of living and breathing electronic circuits and I can finally say mission accomplished. The entire project is complete and thoroughly tested. I have been through many many changes and the outcome is much stronger than I originally conceived. Decide for yourself by watching the movie and then let me know what you think!
Pricing is very close to being figured out. When it is, I will have it on the Farm-It-Out page. It won't be cheap with about $150 in parts alone, but it sure works nice!
