Servo driver?

[Don Brown]

Hugh

I would like to see the pics of your clock.

My goal is to build a starting clock with an automatic heat counter that cheep enough for a small club to afford. It must be idiot proof, and built with components that are cheep and easy to get.

My test digits are 6 X 10 inch, amber on black, easily visible at 200 ft in direct sun light, well within IMPBA specs.

The biggest problem I have seen with LED starting clocks is view angle. A floating clock with the wind blowing can very hard to read at a quick glance. My prototype has a 100 deg view angle and the each of LED arrays are rated at 8000 mcd, which is equal to an automotive break light.

DonB

 

[hugh hargett]

If thats a problem then you need to go with the diffused leds the clear/red type simply do not have a wide angle of view. Ill pm you some pictures of the clock work. 6x10 digits will be really nice. You need the leds with a solid red appearance. Pm me so we dont take Tims thread off topic.

Hugh

 

[Jim Caldwell]

David, now you are on the fast track, I been wondering when someone was going to take this step. Some basic info to get you started from 25 years ago when I started testing GP motorcycle engines (TZ 250 Yamaha).

1. Stable water temperature- gains on the order of 8-10%. 180F for this motor.

2. EGT there was a range of about 150 F that produced good reliable consistent power, hotter was more power but risked seizure. we ran the TZ from 1050F to 1200F seized at 1250, probe 9" from 2" bore piston center.

3. fuel control, we used slide carbs with the mixture needle attached to the slide to control the fuel throughout the throttle travel, but 3rd channel tied to EGT should work fine for this application once you have a stable water temp.

Nitro content, not so much oil, pipes, head design, props all change the motors wants of course but once you have base line runs from the Eagletree data logger you will narrow the progam paramenters very quickly.

Then you are all set, no more falling off the pipe, stalling on course, fighting the needles ect. The engine will be stable.

 

[hugh hargett]

It just doesnt get easier than this TIM.



Now Tim unless your like myself and have nothing better to do but play with electronic projects why would you get into learning code and all that for one simple project. Built this or a similar analog project(simple parts from radioshack prob under 10 bucks) and move on. For me it wasnt an issue of scaring anyone or intimidation its a matter of practicality. Davids needs and your needs are very different. When David has refined his project it will be full blown with telelmetry and things like that so yes David needs that power. The small unit that you guys are looking at are very powerful 16 and 32 bit systems in the right hands and I encourage experimentation if thats what you want,but if you just want what you want dont overcomplicate it.

In your app Tim youd simply replace the one pot with a two resistors and a toggle switch that toggle between the two resistor values which you make the same as the endpoint resitance values of the pot.

Quoted from a famous cook "BAM"

 

[hugh hargett]

David, now you are on the fast track, I been wondering when someone was going to take this step. Some basic info to get you started from 25 years ago when I started testing GP motorcycle engines (TZ 250 Yamaha).

1. Stable water temperature- gains on the order of 8-10%. 180F for this motor.

2. EGT there was a range of about 150 F that produced good reliable consistent power, hotter was more power but risked seizure. we ran the TZ from 1050F to 1200F seized at 1250, probe 9" from 2" bore piston center.

3. fuel control, we used slide carbs with the mixture needle attached to the slide to control the fuel throughout the throttle travel, but 3rd channel tied to EGT should work fine for this application once you have a stable water temp.

Nitro content, not so much oil, pipes, head design, props all change the motors wants of course but once you have base line runs from the Eagletree data logger you will narrow the progam paramenters very quickly.

Then you are all set, no more falling off the pipe, stalling on course, fighting the needles ect. The engine will be stable.

Jim, I want that 225 pound superbike can i get it? I know what a tz250 is quite well almost a 20 thousand dollar 250 that you can **** near lift over your head.

David looks like you may need to start a thread on your project.

 

[hugh hargett]

Tim how many ways you want it?: http://www.555-timer...rvo-tester.html

 

[Don Ferrette]

This thread has been cleaned up. ENOUGH of the verbal sparring. No replies to this are needed or wanted, just remember this is supposed to be fun.

 

[hugh hargett]

Okay Tim and David the floor is yours.

 

[dwilfong]

My thoughts are making one circuit to gust stabilize the water temp.

And one to control the EGT with the needle right on the end of the spray bar.

I think theses are the two thing that will give the best results with the least amount of complication to the system.

Should make tuning and code writing very easy.

The third channel can still be used in the system to fine tune the the needle control system for different eng setups.

I think that EGT and head temp are the bottom line to eng performance with are engs.

no need to make it more than what it needs to be.

So who is game and wants to get on the same page and do this. the more minds involved the easer it will be.

David

 

[Bill Green]

A simpler 555 timer cuircut

 

[Charles Perdue]

My thoughts are making one circuit to gust stabilize the water temp.

And one to control the EGT with the needle right on the end of the spray bar.

I think theses are the two thing that will give the best results with the least amount of complication to the system.

Should make tuning and code writing very easy.

The third channel can still be used in the system to fine tune the the needle control system for different eng setups.

I think that EGT and head temp are the bottom line to eng performance with are engs.

no need to make it more than what it needs to be.

So who is game and wants to get on the same page and do this. the more minds involved the easer it will be.

David

I appoligize for disrupting this good thread earlier.

I do have something constructive to add to it though. I have a mechanical thermostat that I designed and built for our boats that works very good. The problem has been in the difficulty in the calibrating of it to a specific temperature with the boat running at different speeds on the water. On the dyno that I am now building, I have 2 temp gauges, water in and water out, a variable speed pump and an a cylinder head temperature gauge so that I can find the best temp for our engines and calibrate the thermostat for this temp. It will be another one of the items that I will have for sale when I have it finished.

Charles

 

[dwilfong]

Charles

That is why I was thinking a servo controlled system that reacts to the head temp. the speed and load would not make a difference as the servo could adjust to the changes very quickly.

Would just have the valve close to the head or on it.

Mechanical would be much simpler. but will it reacted to a load in a corner at speed.

When I logged head temps with my eagle tree it looked like a square wave on a scope.

kinda funny looking. you could see every corner in the graph.

I will dig one up and post it.

David

 

[hugh hargett]

Tim, come on back into the fold this is your thread lets get you a servo driver.

 

[Tim_Duggan]

Sorry for the delay - I'm in Australia which is on a different time zone to the US. At the time of me posting this it's 9.30am.

Thanks for the schematics guys - I haven't had a chance to look at them yet - just thought I'd fire in a quick post to explain my absense from the conversation. Will be back shortly!

 

[dwilfong]

Charls that Spark Fun mini is the shizzle. Have you messed with it any.

I see thy have K coupler and driver board.

David

 

[Tim_Duggan]

First off I don't know what happened that required Don to apply a clean up, but wanted to say thanks to Don for doing so and not killing off the thread. I'm happy to see that others have similar thoughts and input, and this turns into a collaborative effort on IW I'd be very, very happy. As anyone who knows me can testify - I'm not the type to keep speed secrets.

OK, down to brass tacks;

I think the smaller Arduino's are the way to go for multiple control aspects. From what I can see, the programming is fairly straightforward and there are loads of free libraries and web forums for help from the Arduino community. They are available in small sizes which would be good for boats like 21 riggers too. If we wanted to get really carried away, they could drive a stepper for automated variable pipe length to take advantage of that change in EGT we see in corners However, for my initial "proof of concept" I want to solely play with the water on a 21 rigger as I think that would inadvertently have a positive effect in the other areas too. If I can keep it simple and light, it should show if the extra weight and effort is justified. Assembling a simple circuit is within my ability right now. Programming an Arduino would take some learning on my part first. If someone else already has that "know how" and would like to do the programming for me, I'd go straight to an Arduino and forget about the servo driver test. What I'd need is for the input from the thermistor monitored, and when resistance excedes value X, the servo is moved about 90 degrees, and when the resistance falls back below point X, the servo returns back to it's home position.

If a mechanical thermostat was smaller, lighter and did a reliable job - it would be more beneficial on small light boats than a servo / controller based system - but then again I think bypassing the water from the head and having a servo switch it back into the head would give the fastest response temp wise and would minimise any pressure related issues to the cooling system.

Using a valve like the Perry wouldn't shut the water off completely like a bypass or a thermostat, and while it would heat up/ cool down faster than without it, it wouldn't be as fast as a bypass as any water in the head would stagnate completely.To do the mixture valve / servo / thermocouple deal is possible now with off the shelf items as has been pointed out. It's not what I want to do though as I feel there is room for improvement.

Tim

 

[Greg Moss]

Tim

Some thoughts that come to mind on the temperature and control question;

When designing controllers for cooling fans and other devices in the past, the hysteresis of the control became important for component reliability and stability. That is; Temperature exceeds your set point and fan switches on. Within a very short period the temperature falls below the set point and the fan immediately switches off again if no deliberate delay or hysteresis is employed.

In this application, would you want an instant response to smallish temperature changes once the set point has been reached to keep the temperature of the head very tightly controlled? Just wondering about the combined effects of the interaction of temperature change, performance and mixture. How far does mixture shift when you're actively controlling temperature?

I wonder how rapidly temperature changes in an engine head when water is removed or regulated once the engine is already warm and performance of the engine is already close to the peak of its envelope?, or is the rate of change relatively slow due to the heat sinking effects of the crankcase, etc.

Some bimetallic temperature sensors are available which act as open/closed control input devices and have some value of hysteresis inherent through design. These might simplify some elements of the design. It would depend if you needed that, I guess, rather than a continuously variable thermistor device. Both could be mounted easily enough.

cheers

 

[dwilfong]

Tim the Perry valve will go from completely closed to completely open in less than half a revolution. and yes it dose close off completely.

It has a v cut orifice on a tube to do this kinda like a K&B carb spray bar.

David

 

[Charles Perdue]

David, I am not an expert on them, but I have played with several of the ardunios just to see how they work and what they are capable of. The application that you use them for depends on whick one that you choose, how it is programmed and wired.They are like your own micro computers that you can customize just about any way that you want. They are well within your ability to setup for your idea for multiple controls.

Tim, the mechanical thermostat only weighs about a 1/4 of an oz and is small enough to fit in just about any boat. It is as quick as a servos response time, quick enough to control the cylinder head temps all around the course. When I complete my dyno, I will finish the developement of the thermostat. Just too many projects in the works.

Charles

 

[Tim_Duggan]

Tim

Some thoughts that come to mind on the temperature and control question;

When designing controllers for cooling fans and other devices in the past, the hysteresis of the control became important for component reliability and stability. That is; Temperature exceeds your set point and fan switches on. Within a very short period the temperature falls below the set point and the fan immediately switches off again if no deliberate delay or hysteresis is employed.

In this application, would you want an instant response to smallish temperature changes once the set point has been reached to keep the temperature of the head very tightly controlled? Just wondering about the combined effects of the interaction of temperature change, performance and mixture. How far does mixture shift when you're actively controlling temperature?

I wonder how rapidly temperature changes in an engine head when water is removed or regulated once the engine is already warm and performance of the engine is already close to the peak of its envelope?, or is the rate of change relatively slow due to the heat sinking effects of the crankcase, etc.

Some bimetallic temperature sensors are available which act as open/closed control input devices and have some value of hysteresis inherent through design. These might simplify some elements of the design. It would depend if you needed that, I guess, rather than a continuously variable thermistor device. Both could be mounted easily enough.

cheers

Greg,

Thanks for the input!

From previous experience with controlling temps in a crude manner, they do seem to reach a point where they level out when the needle comes into it's own. I'd initially set the switching point ever so slightly higher than that levelled out temp to minimise the system fluttering back and forth, and control the flow of the "open" state purely by the ID of the water fitting in the rudder. The way I'm planning on doing this, the switchover point should be noticable from the shore by the water streaming from a different outlet.

The bimetallic sensors you speak of, do they encompass an open / closed state at set temps? If so that would make the whole thing very simple. I'd just need to use a logger to establish the temp required. Do you have any links? The bimettalic temp switches I use @ work are non- resetable and act as a fuse - therfore no good for this application. I must admit I was only thinking of using a contact thermistor from a photocopier fusing unit as the sensor. Will easily cope with up to 200degrees C and will give a readable change to resistance all the way down to ambient. A bimetallic switch would work better.