Member postings for Joseph Noci 1

Unless you have a 'good' quality OCXO, don't spend to much time on the 'time-to-digital' type of PPS jitter measurement circuits.

The Lars cct types, using an RC charge network and reading with an A/D in the processor needs careful design and layout to ensure cct noise does not influence the reading. For an average OCXO, it is a lot simpler to use a frequency lock type loop - 1PPS starts an overflow timer ( clocked with CPU clock..) and the timed residual is read at the next 1PPS - the residual relates directly to the 1PPS jitter and this is filtered in a slow IIR filter in the cpu. Use that to generate a PWM output, integrated to DC to drive the OXCO voltage control input. - maybe 5 or 6 chips plus a GPS...Before getting anxious re the CPU clock drift, tempco, etc - that add a very useful external shift to the counter operating point, and helps overcome the hanging-bridge control point on the OCXO...

The original GPSDO fellow was Brooks Shera - here is his original concept, using external counters - newer micros allow all that internally.

Brooks Shera GPSDO

This fellow has very good info and a useful design:

VE2ZAZ GPSDO site

and

**LINK**

GPS devices such as the UBLOX 7 and 8 series , with TCXO, can be programed via the serial interface and the UBLOX free SW tool to setup the 1PPS output to output almost any frequency. The base frequency in these units is 48MHz, so any output that is not an integer divisor will have jitter on the waveform. 8MHz seem to be 'jitter free', but is a nasty frequency - needs feeding into an Si5351 PLL set to give 10MHz, etc...still with some jitter. However, feeding an external PLL (4046 type) with a long time constant can result in a very clean low jitter signal, so that is another way to get frequency much more stable than you arduino table top clock, but not 'true GPSDo' quality...I am sure it will suffice for the pendulum measurements!

This is a good read, and shows the hanging bridge issue - pg 23

**LINK**

I have built a few GPSDO's - one with an old HP OCXO of very good performance (from a Tube Defunct Ceasium Beam standard), and one with a very good but not as good as the HP OCXO, new, from Golledge in the UK.

I have used the Freq-Lock loop method, the RC '1ns' resolution A/D method and a Texas TID chip, with 100ps resolution - some very good Allen dev results...

BUT, Beware!! if you start down this road, the next is a stop at Time-Nuts and then its tickets....You will chase that elusive extra 10 minus 1 down a long road to lost time...

Edited By Joseph Noci 1 on 02/01/2023 11:31:02

Maurice - payback of the system is also very dependant on location - Electricity is rather cheap in Namibia compared to Europe, so as I mentioned to Keith earlier, it would take 26 years to recover costs on my system. Also, as mentioned, that excludes costs to replace batteries, which may cost less in the future but right now are pricey. So not a money saver at all in any normal lifetime here.

Neil - No I cannot sell to my neighbour - I have to 'sell' to the local power provider at around 45% the going rate, and as mentioned, don't get paid for it, but get credits that reset to zero each month - so I cannot build up credits to use in winter either. Robbery, as far as I am concerned..

We have a lot of mist/low cloud cover here from May/June to Sept/Oct, and the simulations show 16/18KW/hr from the panels in December to Feb( during peak sun periods), down to 5/7KW in July.

In Windhoek, about 450KM inland, the tarif is 80% of our coastal tariff, Solar systems that re-supply the grid there get 90% credit for each unit...supposedly because the income from coastal regions is low due to low population on the coast.

And a few other shenanigans we won't go into..!

Not to go to far off topic...Namibia is today one of the safest countries in Africa - and Swakopmund even more so - there is no tangible 'race' issue in this town at all ( maybe a German/Afrikaner one though...) - Nothing at all like in South Africa, or anywhere else in Africa..We probably have our small population to thank ( less than 2.7million people..) and the fact that the central and northen regions are basically desert. Land grabs gain no-one any thing here - its just more sand...

Anyway, this post was I guess to brag that I am trying to do a little where I can...

Yep, tried it a short while ago and it works fine. A 10uf cap gave about 3/4 speed, and a 2uF cap around 1/4 speed. The latter took about 4 seconds to get to speed.

SOD - ...and the motor slows down because the windings are out of phase..

How would that be? The motor itself is inside the power feed circuit and does not know about any phase shift, ie, across the 'live' and 'neutral' connections to the motor a scope would show the same phase relative to the existing 10uf phase shift cap - the phase shift you speak of would be relative to the Live side of the added cap...

Thanks all for the guidance.

Joe

Thank Michael - we will see in time if it impresses me...

Keith (Wyles) - Over what time period will it return your initial outlay?

There is NO chance of return AT ALL! The system is idle now in summer - I am sure it will work hard in winter, and the batteries will be heavily taxed. At my current annual electricity rate, I will break even in 26 years time. And that excludes battery replacement in that period - to replace that pack today is around 15K Pounds.

Harry:

You may think you are saving the planet but I wonder how big the carbon footprint is for all you gear

Not sure I follow. By 'my gear' I presume you mean my machinery? Using the machines,unless one wishes to be pedantic, would not increase my footprint, if I ran from my own generated solar power, surely? The emissions that resulted from the manufacture of said machines is will not grow, nor will the emissions from the manufacture of the Solar system - although replacement batteries means being part of the carbon cycle in the manufacture of the new set...

I don't really understand what you are implying Harry - please explain.

Yes, it would be nice if 'new safe centralised power' came along but I don't see that happening within this century - Even though the entire first world has had the Power Plug pulled from its socket, there is very little real happening to fix the problem - lots of talk and posturing at many summits, while coal mines are re-opened all over the world and the perpetual approach is - lets get through this winter and we will worry about it next year..

And in Africa, power was always and remains a problem for all. Government mentalities in Africa are focused on get rich quick and are fraught with corruption. Namibia obtained 65% of its power from South Africa , on a 6 year contract basis, previously renewed with no issues. The current contract expires end 2023, and SA have said they will only renew for two years, and this time on a non-guaranteed basis - ie, Namibia will be subject to the same load-shedding in place in SA. There is ZERO maintenance taking place on SA's power generation infrastructure with the last new generators installed 27 years ago...SA endures 8 to 10 powerless hours a day, 4 to 5 days a week at the moment, in the major cities...How to destroy a country and its economy....

Its all well to talk of the nuclear powered, wind powered, etc, first world - that may come about when your grandchildren are your age, but it will NEVER happen in Africa or any of the third world.

So even though my 'little' bit is very little, and irrelevant in the scheme of things, when SA pulls the plug on Namibia, and perhaps in the dire times Europe and the UK find themselves in now, and for the foreseeable future, I will still be able to play happily in my workshop!

At least I have a reasonable level of independence, and at the same time am saving a few kilograms of carbon emissions!

Perhaps not appropriate on this forum, but pertinent in this time of world energy crisis!

I have in the last week completed installation of a 20KW Solar system. It has been running for a week. It performs very well, but is is summer now, so that is not a good test yet!

We do have regular cloudy and very misty days here on the coast, and since commissioning on the 12th, we have had 3 days of solid mist with the rest bright and sunny.

At 10.00am during the mist days the system provided 4 to 5KW, while at midday with visibility approx 400meters in the mist, power was 6 to 7KW.

Batteries are 6x5KW/hr Lithium, dischargeable down to 20%. Discharge has been to 58% min at present - using oven, coffee machine, stove etc at night. Geyser is on a timer - 8to10am and 2to4pm, set to 45degC

As I have 3phase lathes, shaper, woodworking machines, etc, the system consists of 20KW of PV panels, with a possible 6KW more to come, a FRONIUS PV to 3Phase inverter ( 15KW) , an MPPT PV to 55VDC charger for batteries and three 10KW 3Phase inverter/chargers.

The latter take DC feed from batteries and when batteries are charged , DC feed from the MPPT battery charger (a 200amp/55V charger). These inverters also reverse roles and can charge batteries when needed.

The PV panels are in three strings - 2 of 600volt strings feed the Fronius 3PH inverter, and one string at 400volts feeds the MPPT charger.

Excess power is fed back into the mains grid.

Unfortunately, our power supplier is behind the times and cares nothing about our carbon footprint...They gladly accept my excess power ( some 10KW/hr for 6 to 8 hours at the moment..) and give me a credit for it - they won't pay me money for it, but credit against my use of their power. Also, they credit at 45% of the sold tariff only, so I have to give them two units to get almost one unit credit...AND any credit I have at the end of a month is lost..does not roll over.

2x600V strings on the ground floor roof.The 1x400V string is on the roof of the 2nd story

Power room - left 3x DC-mains inverters, then (grey box) Fronius PV to 3PH mains, then MPPT DC Charger and right side the main DB

3PH 10KW each DC to Mains inverter/chargers

PV to 3PH mains @ 15KW

MPPT PV Charger, 200amp

6 battery stack 5KW/hr each. Intelligent monitoring system in each pack.

Space above for the next 6 batteries..When I add the 4th PV string upstairs..

10.5KW today at 10H00 this morning

Control panel LCD at various times and loads..Still tuning and playing..

upper left is the national grid - minus numbers are feed into the grid from my PV system. Positive number would be from grid to me.Critical loads are house and workshop - AC loads are underfloor heating, currently off in summer.

I even ran my big 3ph mig welder from the system at 250amps - all it did was halve my power export to the grid!

There are 3ph power monitors on incoming/outgoing grid and on the critical and AC loads and all that data as well as power generated, PV power, battery condition, etc is logged and accessed by network interface. All very neat...

Thanks Martin - Will do!

Appreciate your comments.

Joe

I have an AC motor fan I wish to use to extract air from my solar power electrical room. The fan is a 220v 1amp AC motor , with a 10uF cap.

It works fine in hot weather with the solar inverters running hard, but in cooler weather its speed is excessive. Fitting a 10uF AC cap in series with the live lead slows it to a very suitable speed. Is this a safe practice? Are there any reliaibility issues I should worry about?

Built a pneumatic rivet queezer - I use 3.2mm semi-tubular aluminium rivets in the mnfr of Lion tracking collars here in Namibia. I have so far manually squeezed about 8000 rivets in the past 4 or 5 years...I am also changing collar strap material to a much tougher material ( biothane) as the Lions keep biting through the collars..Which mean new molds for the epoxy encapsulation of the electronics, etc..So while busy with it all, I made a pneumatic riveter - used some Festo products - a double acting cylinder, 80mm diameter piston, so adjustable restrictor valve to slow everything down to my speed, and a foot pedal. It works like a charm...

The two rings with rod holes allow exact setting of river squeeze length - photo below, right.

The rivet snap is removable as well. Also, the snap head is spring loaded, about 10mm of spring depression before the rivet starts squeezing - giving me time to line the snap pip up with the rivet tubular inlet.

Bunch of test rivets for length, snap profile testing, etc.

Previous collar material - A high strength belting, but not high enough..! Hand squozen rivets!

Edited By Joseph Noci 1 on 19/12/2022 11:54:18

Thought I was alone in that...

Some nifty calculators and graphic tools..

**LINK**

!!

Referenced in HMEM forums as well

PM Boring table

PM archive here - looked at all 12 -1941 issues and did not find the table....Fun reading though, although PM seemed to be rather War oriented back then...

PM Archive

Maybe MichaelG will find it for us - I am also interested.

Thanks Jason. That was another post that zoomed of the list to quickly for me to see..

Joe

Most times I log in I first pop down to the 'Album latest photos' block down the page - when a photo interests me, I click and dig to find its thread, which may have scrolled down the post page already.

The latest photo's are now very late...unless I click on 'more latest etc...'

Something stuck?

Joe

Edited By Joseph Noci 1 on 28/11/2022 09:08:19

You did not mention the stepper phase drive controller or a step/direction pulse generator, so I am assuming you don't know how steppers work - If I assume incorrectly, I apologise...

You need a DC power supply 20 to 40VDC or so at a few amps - The S350-60 is that PSU I think. Then you need a stepper drive controller - feed that with DC from the S350 supply.The Stepper controller has 4 wires out, 2 to each phase of the stepper motor - the 4 wires you mentioned.

Then you need a pulse generator that send pulses to the STEP input of the stepper controller. The controller then drives the 2 phase outputs as needed by the stepper motor. The pulse rate determines stepper rotational speed. The controller also has a direction input - logic HI makes the stepper go one way, logic LO , the other way..

So before you get to simple on-off-on and microswitches, you have to sort all the aforementioned goodies out first.

Lots of info through google, and we can all help here too.

https://www.damencnc.com/en/advanced-digital-stepper-drive-em422s-36v-2-2a-2phase/a3690

https://learn.adafruit.com/all-about-stepper-motors/types-of-steppers

Edited By Joseph Noci 1 on 21/11/2022 15:29:31

Large drills and Diamond are not a good mix - any diamond wheel used where reasonable heat results, as would probably occur with large drill tips due to greater pressures, duration, etc, The diamond grit transforms under high heat and contact with carbon and the grit contact edge begins to converts iron carbide and a form of graphite - not very good at cutting. common at temps above 700degC to 800degC at the contact line - not difficult to reach.

CBN for steel, Diamond for tungstens is the general rule, but for small drills, maybe sub 6mm or a little larger, keep working pressures low, or use coolant, then diamond will be fine.

Probably violate forum rules, etc, but ...

A happy friend in Johannesburg obtained a dozen or so size A holders and the toolpost from these folk in June.

**LINK**

He says the holders also fit his orig Swiss toolpost just fine...He was also very content with the pricing..

Looks exactly like the Createtool product - maybe they renamed or were incorporated?

The taper angle would need to be rather steep to prevent the wedge becoming stuck in the taper slot and I don't think the unimat column could take that comfortably. Unless sound machining capabilities are available, small variations in slot width or taper will cause the wedge to bind as you wind the head up and down. Average machining will do as long as the slot is truly inline with the column, then a brass tapered tip lock-screw will do just fine - it's a small machine.

Yep...