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Topics - BruceM

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General Discussion / Welding on clean DC
« on: May 25, 2019, 12:42:31 AM »
I bought a new group 29 "marine deep cycle" battery to give the clean DC, 24V welding thing a go. They are rated 385 cranking amps so a good match for 100+ amp welding current, and they are what I have in my 120V battery bank now.

I made a 600 uH choke from a gapped 1000watt laminated toroid core; 22 turns, 16 feet, of 6 strands of 12 awg. I gapped the core with a 10" abrasive chop saw blade in my table saw. I only lost 1/4" of blade on the job, but it took 4-500 gallon tanks of air to make the cut.  I filled the gap with steel filled epoxy. To save some $ on the trial, I used some heavy jumper cables for welding cables. 

The exciting news for me is that yes, I can do it. While regular welders have me running for the hills from EMI headache, this was doable for me.

Welding on 2-12V batteries does work, and as the article I found by a welding enthusiast stated, the choke makes it possible. When I bypass the choke, it's just not possible to maintain an arc and get the puddle going. Alas, I seem to be a bit lower voltage than I'd like- no such thing as long arcing with this setup!  7018 (3/32) rods were a bust, could not maintain an arc and liked to stick and melt the rod. 6013 (3/32) worked, best with positive on the electrode.  I'll have to set up some meters on volts and amps and get my neighbor to watch them while I do a practice bead.  I'm ordering some 1/8 rods- more current may have better arc length and stability.

I suspect the losses in the jumper cable are not helping, so I will pop for some fat and short welding cables.  I may also reduce the turns on the choke.  No need for that much inductance, but I goofed on calculations when shooting for 250-300uH.  Battery and all cables were cool immediately after a 6 inch test bead. 

I'm very rusty, my last stick welding was in 1974.  I think with some practice and some fine tuning of the setup, I can do my own welding again.


Generators / ST-3 is out
« on: January 22, 2019, 10:16:55 PM »
My ST-3 is out, won't operate on the harmonic winding system either, and flashing the FC dinn't change anything.  I did use the generator yesterday and it worked fine.  So far I'm baffled. The static (off) testing of brushes and slip rings looks good, field coil resistance is OK, harminic winding resisitance is OK, stator resistance winding is OK, my other various switches, fuses and relays OK.

Came in for late lunch, meds, and a study of the circuit diagram.  The bridge diode is a modern 800V unit so highly unlikely to have failed. I'll have to start using my handheld o'scope with a 15 foot extended probe lead and see what's gone wrong with the spinning harmonic signal while I stand outside.  It's cold, cloudy and windy.

General Discussion / snowed in, again
« on: January 13, 2019, 04:06:22 PM »
More cloudy and cold stretches this winter than we've had in 20+ years, and last night a forecast 0-3 inch now has turned into 8+ and still snowing this morning.  This just after the last snow finally melted.  I'll be on PV and solar hot water snow removal when/if it stops.  An alarming change after over a decade of milder, warmer winters (and hotter summers).   

Lucky for me a friend brought groceries 2 days ago. There's no county maintenance on our dirt roads here, it's DIY all the way.

Massive PV to the rescue.  With my additional 1500W, despite heavy overcast (though with snow on the ground assist) I've got plenty of power to charge.  By the time I finished shoveling snow, my main battery bank was up to bulk charge voltage. 

General Discussion / cold weather gear motor lube
« on: January 10, 2019, 07:13:30 PM »
I had a failure of the 5 rpm gear motor actuator which I use to control my projector focus.  Focus control is needed as the Qume Q5 focus is not temperature stable. it's a 24VDC rated little can type brushed motor I operate on 12V.  It stopped working when it got cold, even at 40F the motor would not start.  I use a modifed 2 channel IR receiver to control the gear drive, since I already have IR extender control of the projector.

I took it apart the failed gear motor and found the motor, brushes and commutator are clean, and the motor starts and runs freely at 12v in both directions.

So I'm thinking that the black grease which covers all the metal gears, and the worm drive which is on the motor shaft gets so stiff in the cold that the motor can't spin up.  Spin up is not aided by the two pole commutator. 

I'm thinking of cleaning out the grease and putting a bit of ATF on the gears.  I'm also going to boost the voltage.  I think there's some 19 or 21VDC for the projector I can use. This is not a high stress application and it only runs for maybe 30 seconds a day.  Any other ideas?

General Discussion / IDC connectors suck
« on: December 16, 2018, 11:45:10 PM »
I spent a few hours troubleshooting my remote fiber-cellphone hardware today. My memory is so poor it's a relearning project, though fortunately with pretty good documentation. The fiber-phone was a 2006 project, all hand soldered, no PCB, with a Picaxe M18 controller.  Ended up being one of the few Molex insulation displacement connectors I have left on that...on the 12v power to the solenoid that pushes the button to turn on the cell phone.

I never use Molex IDC connectors anymore, for good cause.  The contact to the wire is just not reliable over time. 

Not much fun working in the cell phone dog house when you're having a bout of Graves and your heart is going 100 BPM and your hands are shaking. 

Everything else / DIY Low EMF 5 step Sine Inverter
« on: July 29, 2018, 03:12:30 AM »
I thought I should play nice and quite stuffing this in Glort's PV -grid tie work.  While I did add 1500 watts of panels to my existing 875 for this project, I'm now down to the inverter work.

A little review:

I live off grid and have lived with my own 120VDC system and Listeroid for AC and compressed air for a long time.  In preparation for adding inverter power to my system, I upgraded my 120VDC PV charge regulator to handle up to 3000 marketing watts of PV.  It's linear, not pulsing, for very clean DC.

My 120VDC input inverter design is based on the venerable Trace SW series which does low frequency switching of transformers with secondaries in series to create a sine.  That general concept is about all I'm using.  I'm using very soft (slow) switching plus snubbers and minimal passive filtration to generate AC with no audible (via AM radio) EMI on the AC or DC supply.  I'm only using 2 transformers of equal output secondaries, and they are used to make a 5 step sine wave; zero plus two steps up and two steps down.  I originally did a 7 step sine but found 5 step better. The 5 step sine gets the THD down below my ST3 generator head, and eliminates the typical 20% motor heating loss of a MSW inverter.  I use 120VDC for my home and shop power, and have been using a Listeroid 6/1 for AC generation for well pumping and washing machine.

I have previously done quite a bit of testing of the prototype on motor starting at 120VAC output; it would start a 1.5HP tile saw like grid power, instant and effortless.  I ran into a bunch of trouble when I switched transformers for 230VAC output; ultimately I tracked it down to huge inrush surge current.  Until I worked up a software solution of soft starting the transformers, I could only test by starting the processor and H-bridges with 0 volts input, then switching on the 120VDC through two huge chokes and 30K uF of DC filter caps. This provided a slowly increasing voltage which kept inrush current minimal. The massive DC filter was needed for keeping AC off my clean 120VDC. With the filter in place, I now have 1 millivolt of AC ripple with 1000 watts of load.  Backfeeding 230VAC to my step down transformer outside the shop, I've run a couple loads of laundry in the washer (about 1100 watt load also) with no trouble and barely warm heatsink on the H-bridges.  I've also been testing with 500, 1000, and 1500 watts of heat lamps in the shop.

I got the prototype jury rigged on the floor of the battery bank shed and then found that due to my new short 120VDC supply wires to the 10K uF fiter output capacitor, the old Antek transformer inrush current problem came back and bit me.  I should have tested with small fuses, but I got cocky...with 4 mosfets, 3 ICs, and 2 transistors fried the result.  I got it repaired, changed the soft start to extend from 50 usec to 5 millisecond pulses, and now she starts and stops nicely on small fuses, again.

Tomorrow I'll test on my 1/2 HP Franklin submersible well pump. It pumps from a depth of 200 feet.  It normally runs at 1150 watts, with starting peak over 3400.  The issue to be tested will be surge load capability and compatibility with the operation of the Franklin QD solid state capacitor start relay.

Listeroid Engines / Icreasing rpm of 6/1 with SOM flywheels
« on: January 11, 2018, 02:35:02 AM »
I'm thinking of leaving my 6/1 on diesel for now instead of doing a propane conversion.  My new SOM wheels are 25  inch diameter so I must increase the ST-3 pulley size.  Since it worked out well for my neighbor's machine, I'm going single B belt.

At the same time, I'm considering a modest increase in RPM- say to 700 (ish) rpm.  This will benefit my air compressor which was being driven well below it's max rated speed. 

Are there any hidden surprises I should be thinking of?  My 6/1 has the iron piston.  Adjusting counterbalance weights on the new SOM wheels for a smooth run isn't be a big deal for me.

The B belt riding flat on the flywheel gives it an effectively large diameter compared to belt on the pulley vee shoulder.  So 1800 rpm at ST3 over the pulley ratio of 25.6"(SOM flywheel effective dia with B v-belt and no grooves)/10 (pulley size at ST3) gives me 1800/2.56 = 703 rpm engine speed.  A 10.25" pulley should give me 720 rpm. Either would be OK for my air compressor speed with existing 19" drive pulley.

Any helpful thoughts or gotchas I'm missing?

Listeroid Engines / SOM flywheel upgrade!
« on: October 19, 2017, 02:06:40 AM »
Thanks to 38ac I got connected with another member Robert Leonard, who had some SOM flywheels for sale.  Bob did a great job of securing them to a sturdy pallet and getting them loaded on my freight carrier 8 days ago.  Today I picked them up at my local helpful Ace Hardware.

They are now on my shop apron ready for some clean up and new paint! They are a bit shocking to a someone only familiar with Rajkot castings; there are no voids, putty, bondo!

I'd like advice on your favorite rust treatment that does not involve Rustoleum type oil based paint.  I just can't stand the stink of it. I'm thinking sand and wire brush, naval jelly, then paint. I'm in AZ, USA, so continued rusting is not a big issue, I'm just proud of them so want to pretty them up a bit.

Generators / CGG ST heads- warning- aluminum windings
« on: August 24, 2016, 02:09:32 AM »
Dear friends,
We recently had a open circuit failure of one rotor coil winding of an ST-3 head from Tom at CGG.  Since he didn't have a replacement coil, we ordered the matching 19 awg magnet wire and after winding it found the resistance didn't match, and it was much heavier. Checked closely and found that the windings in this year old ST head are ALUMINUM.

I'd also like to add that the windings were not redesigned for aluminum; they are the same 19 gauge as the copper in my older ST-3.  The copper windings are 4.3 ohms per coil, these are almost 7 ohms.  I'll be checking the stator windings later today, but I expect the same was done there.  Visually they look identical, which was not doubt the intent. 

I'm now looking for an all copper ST head replacement.  Does anyone know of a reputable importer of all copper ST heads? If I'd known this thing was aluminum I would never have recommended it.


Generators / Frequency/Voltage Meter for ST gensets
« on: April 14, 2016, 04:12:39 PM »
I've been disappointed with the analog panel meters for AC frequency and voltage from China.  The frequency meters in particular are junk- when voltage goes down (with increased load and thus lower frequency), the frequency meters show an increase in frequency! Laughably bad design.

Many digital frequency meters have problems with the ragged waveform of the ST generator heads.  They will not display the proper value, or even close.

I did find one cheap ($10) digital meter that is quite good:

Both frequency and voltage are displayed properly and accurately on an  ST-3 head on harmonic.  Voltage is RMS, tracks a Siemens ($) display within a volt.

Generators / CGG AVR- not so hot for non-linear loads
« on: March 23, 2016, 02:15:41 AM »
Hi Guys,
We're using the CGG AVR on my neighbor's ST-3 with propane converted DES 8/1.  It is using the Harmonic winding as the excitation source, since it just doesn't work at all using one leg of the line voltage (can't start even a 1/2 hp motor).  Tom lists that configuration, but frankly, he should not.

On the harmonic the CGG AVR works fine on induction motor loads, but on non-linear loads like a small wire feed welder, or a Vitamix on (electronic controlled) low speed,  it regulates the voltage so low our RMS voltage monitor trips. (regulates to 170V RMS instead of 240, and 85V on the stepped down 120V supply).  On straight harmonic the ST-3 does fine on these same loads.

So alas, while Tom's price is appealing, the AVR being sold by CGG has some serious limitations:

1. You can use it only with the harmonic winding for excitation.  
2. It regulates only to peak AC voltage levels, not RMS,  and will down regulate to grossly low voltage for some non-linear loads.

Can anyone suggest a 240V AVR that does a decent job of regulation?  Something that says "RMS" voltage in the specs perhaps?

Listeroid Engines / Mechanical water pump ideas?
« on: March 20, 2016, 03:15:55 PM »
We've found that my initial design for cooling, thermosiphon for coolant flow and thermal chimney for air through the radiator is inadequate for extended runs at full load.  From some experiments with increasing the stack height and modest fan on the radiator, it seems our water flow is inadequate.  We are getting 54 degrees of cooling on the return water, but still engine temperature very slowly climbs. Raising the radiator more would do it but then our thermal chimney for the radiator gets even taller, which is a structural issue for high winds.

I'm looking into options for a water pump. A mechanically driven by a rubber roller or vee belt off the flywheel would be lovely; it could also let me lower the radiator, increasing the vertical for the thermal chimney.  Any suggestions on a suitable pump and how to do the bypass so that a thermostat could continue to be used?  

Alternately, can someone suggest a suitable AC pump?  

Generators / voltage monitoring relay - what works on an ST head?
« on: February 25, 2016, 01:13:59 AM »
I tried a Schneider 831VS-240A voltage sensing relay.  It is very unhappy with the no-load ST-3 waveform, even when I added some filtering before the relay.  The no load waveform is close to a triangle wave, a bit ragged.  Massively filtered, to a more curved form, this VS relay is still unhappy, even with a load.  With a 1/2 HP motor on and no or modest filtering  it is happy and works properly.  So it is just not going to work for my application.

I wonder if anyone has found a voltage sensing relay (high, low, time delay trip) that seems to work well on an ST type waveform. 

I have my own voltage range sensing circuitry on my ST-3 AVR but was hoping to just buy something off the shelf for my neighbor's DES propane conversion project. 

Listeroid Engines / Oil level- Lister clone
« on: February 22, 2016, 07:04:38 PM »
I'm a bit baffled about oil level on the DES propane 8/1 conversion engine.  The dipstick is still on the "little door", but only reads what's in the upper sump, so seems useless to me.  What is the proper oil level in the lower sump?  Has anyone tried to put a low oil
float switch in the lower sump? If so, where and how well does it work?

On my Metro Listeroid 6/1 with single sump, a conventional float switch didn't work due to splashing, so I had to hombrew a vinyl oil level sight tube with magnet in a HDPE tube float inside the sight tube, and a reed switch zip tied to the sight tube.  That works fine for both a quick visual check and for auto shutdown sensing, but a bit of a hassle.

So I was just wondering what might work best, and where the doggone full oil level really aught to be on the dual sump clone.

Listeroid Engines / EGT on a 6/1 or 8/1 Listeroid?
« on: January 05, 2015, 03:53:31 AM »
I wonder if anyone has measured the full load (or any load) EGT on a 6/1 or 8/1?

I want to monitor my EGT for my propane mod and would love to have a stock diesel baseline number, for someone closer to sea level and a full load.

I've read that 1250 is the max for normally aspirated diesel auto/truck engines, but I've no clue what a Listeroid EGT might be.

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