Member postings for Steve Addy

Thank you Simon.

Without wishing to offend anyone, people are exhibiting their knowledge and may as well be speaking in Japanese. I'm an amateur engineer and get by quite nicely in that field, but electronics are new to me. There is no point in talking about other processors, I'm playing Arduino period! I am not taking to the road or the main line with 3000hp.

All I'd like is some ideas as to why it doesn't reset in words of one syllable and I'll have a play with the circuit when I'm in a suitable mood.

I did try to look what happened to D2 when a reset was forced with the switch, it appeared to go high, but I was struggling to concentrate as usual. During normal operation it is going low for 30 milliseconds and discharging the capacitor, by way of "heartbeat".

My mother is driving me crackers with constant stupid phone calls, I'm not in the right frame of mind for this at the moment at all!

Steve

I wish I'd kept my gob shut!

Steve

Thanks Neil. As I said I have had that working. At first I read the internal one wasn't reliable hence the 555 steer from a friend. I'd still like to get it to work though.

Steve

I have learned about the voltage drop across a diode Andrew, I don't know why it is there, but it doesn't work without it either.

This is what the article said :-

Once the discharge of C2, is complete, the connection between pin 3 on the 555 and RESET on the Arduino is pulled low, thus resetting the Arduino through the diode D1.

This is a similar circuit on the net **LINK**

Thanks for responding- I hate not knowing about things like this. but it is a whole new world of fascination to me!

This is the original circuit, the values were changed to get it to charge and trigger. Pin D6 and the red LED serve no purpose other that pretty flashing. Pin D2 supplies the heartbeat grounding pulse. It all works but when 555 pin 3 goes low to reset the Arduino, it upsets the device but doesn't reset it. It has to be disconnected after tripping to get a reset to occur. That rather defeats to object!

Fair enough - I'll do that at some point John. It did strike me, but I'd lost the will to live after typing all that.

Hi folks

I am building a WW1 Baldwin Gas Mechanical in 7 1/4" gauge as mentioned elsewhere on the forum. I want to make it fly by wire using an Arduino and servos to control the Eaton Hydrostat and the engine revs. The code wasn't much of a problem and worked within a week of starting from having never seen an Arduino.

However, a friend said, "What if it crashes?" Well you turn the ignition off, I had been more concerned about making it go! What you need is a 555 watchdog timer. A what?

The idea is that a capacitor charges through a resistor, but never reaches the 2/3 rail voltage required to trigger the 555, as a discharge "heartbeat" comes from the living Arduino to drop it back down every 500 milliseconds or so. If the pulse stops, the 555 grounds the reset pin of the Arduino and discharges the timing capacitor to 1/3 rail through another resistor. Thus the grounding pull down time is adjustable and predictable.

Well I found a circuit which didn't work immediately, so I bought a DSO and found the capacitor was unable to charge sufficiently through the resistor specified. I reduced this and watched what happed - going down from 1M to 47k Ohms gave the desired result. I now have the working circuit which trips if the pulse is removed. It will not reset the Arduino though.

I wondered if the grounding period was insufficiently long and performed experiments with a push to make micro switch and the 'scope. The 555 was giving 50 odd milliseconds and not resetting the Arduino, but the switch would do it in less than 4 milliseconds. That wasn't the problem.

I have tried a PNP transistor in the circuit to control the grounding and also a miniature relay due to the success of the switch. Nothing has worked. I have also had a play about with an op amp, but didn't have a proper power supply to drive it. That has been a failure so far, although I have had it following an input in a separate rig.

My mother has dementia and is always harassing me, so I haven't been in the right frame of mind to be pushing back the boundaries of my electronic ignorance recently.

I now have a nice bench power supply and a signal generator to go with the 'scope, but peaceful contemplation is a rarity these days.

I am probably doing something really stupid, but I'm a complete novice in this area.

It is also worth noting that I got the internal watchdog to work on a test setup, but as I have spent so much on gear for this it would be nice to have both levels of reset.

Any ideas would be gratefully received.

Steve

LOL!

Further to my post yesterday, I got a very quick response from the chap concerned. Apparently they haven't heard from Eaton in America, but they have some units to test for a commercial user, so they will include the operating torque as part of it. I will post the results here assuming I do receive them. Fingers crossed.

Steve

Hi John

Not looked on here for a while. I have recently equipped myself with some electronic gear so last night lit the lamps with the proper voltage from a bench power supply. I'll upload the picture of them lighting my bedroom from complete darkness.

Steve

Just sent a final email to the UK agents - I assume they never got a response from America. Two months have elapsed since I last wrote to them!

Steve

Here is the "office" at the present state of building.

Thanks guys.

It is 7.25" gauge which converted from 600mm gauge I make 3.26" to the foot. Not an ideal scale. The LEDs were sourced as filament automotive bulbs will vanish shortly in my opinion and these have a very long life - I bought a spare set too!

The lamp body is 72 of 73mm diameter I can't remember which.

Steve

Hi Dave, I have a 12 tonne hydraulic which was advertised on a well know auction site as a shop press - I got it for £100 as that is US terminology. Think before you use it as it is easy to do a lot of damage.

Steve

I have just finished a pair of these lamps for my Baldwin 50HP gas mechanical. One sat on the "hood" in front of the chimney and the other hung from the rear underside of the cab roof. The body is turned from solid corrosion resistant aluminium alloy.  The bit of wood was so I could take them to the Work in Progress night without risk of damage.

Edited By Steve Addy on 05/03/2016 00:14:17

Edited By Steve Addy on 05/03/2016 00:15:04

I did Loctite and keyways on my loco. That was to get the quartering engineered into the axles and cranks.

I have now bought an Arduino and written most of the code and it happily drives a standard servo in place of the more powerful things which will be needed. I have an all aluminium, steel geared Savox servo of 30kg cm torque to put the engine throttle beyond the control of the driver.

I have written to Eaton in the US, who passed it on to the distributors here; I got a nice reply with the wrong answer. They are now referring the question back to America.

Will win eventually.

Steve

Thanks again guys.

The idea of the Arduino is firstly that I know nothing about them and haven't written a program since the 80s.

I wish to make the loco work by using the gear levers in the cab and the throttle on the "backhead".

This would give the illusion of a mechanical gearbox with two speeds in forward and reverse. I would also like the engine revs to be beyond the control of the driver, determined by the gear position in forward or reverse with idle on neutral.

I haven't given it much thought yet, just weighing up what the servo might cost for starters. Standard servos I am used to are between 3 and 4 kilogram centimetres. I have just been looking up digital servos as I feared they needed a different control signal. It turns out this is down to internal pulses controlling the motor at 300Hz rather than 50Hz. They work on the same signal but have greater resolution and holding torque.

All interesting stuff.

Steve

Hi Michael.

Your reply is appreciated.

I have the Model 7 fitted to the loco and the paperwork for it - I have even made the boss for the operating lever.

However, the only servos I have ever used are the standard type provided with a six channel RC outfit. I'll have to look up the figures for those, make a lever and buy a spring balance.

Steve