Member postings for Malcolm Parker-Lisberg

I found this, and it is appropriate to those considering the ME threshing machine. A Burrel setting up and driving a threshing machine.

See:

**LINK**

Malcolm

Michael

There is an old saying... "It's the volts what jolts, but the mils that kills"

But the voltage is required to drive the current. A blue flash as the short occurs won't give enough voltage to jolt as a weld is most likely to occur between the components.

No blue flash: touch a live wire, circuit to earth through the body will give a jolt and trip the breaker.

The "let Go" phenomenom determines whether you live or die. Less than 6mA and you can let go, more than 22mA, with AC, results in Tetanic Contraction, which means the muscles permantly contract and you can't let go.

30K resistor looks like 3K with the photo colours.

Malcolm

Edited By Malcolm Parker-Lisberg on 28/06/2016 22:59:00

Mike P

Something does not add up in your description of the course of events: A blue flash would trip the breaker, indicating a short to the earthed quill, at this point of contact, in the miliseconds before the breaker opened, no voltage would be available to give you an electric shock. as all the metalwork would be at earth potential !

Malcolm

It means the EU wants to grab the money from Customs Duty for an import from outside the EU. But UK customs allows £25 worth of goods without having to pay any duty, as it costs more to collect than is due. So how decide which way to vote on June 23rd as the EU would like to collect the money, no matter what it costs.

Malcolm

Muzzer

If you are claiming bragging rights, I've got 15 years on you in electronic design.

As a converter, by definition, applies to a SMPS as it converts AC to DC. An inverter takes a DC supply and converts it to AC. You may be too young to remember rotary converters/inverters used during WW2, or even the vibrator.

You demonstrate you lack of ability to read by suggesting that I indicated that the LED was anything other than a DC component. Did you miss the anti-parallel diode, it means a diode, in parallel with the LED connected the other way round, ie. with cathode to LED anode and anode to LED cathode. It protects the LED from reverse polarity. The energy lost due to its presence is small if, by design, the AC supply to the LED is asymmetric.

The Zafira is an example of a lethal motor vehicle that complied to all international standards, but still burst into flame giving people 10 seconds to exit.

Ian

Perhaps they have run out of stock due to our activity, but don't want to admit it.

Edited By Malcolm Parker-Lisberg on 12/04/2016 00:15:56

For the reasons why a toroid is superior to E-I designs and why you can't design out the disadvantages; see the paper by Texas instruments: **LINK**

The difficulty winding a toroid is the major reason for not using them, but the ingenious Chinese seem to have overcome that one.

Malcolm

John

As the saying goes, there are many ways to skin a cat. I don't think they are designed for efficiency, as overall power consumption is so low, but it does depend on the circuit design, a flyback converter springs to mind, inherently output short circuit proof as you can only get out the power that is put in, and a high efficiency design that uses very few components. I have one of those in front of me, sadly demised when I connected the output to the mains. No fires, just dead as a result.

What is almost certain is the the small to medium power copper wound, laminated iron cored transformer is heading for extinction.

Malcolm

Oh dear, sometimes a little knowledge is a dangerous thing. You need to dig out your basic electronic reference books and look up the definition of an inverter.... Converts DC to AC. SWMP are generally DC output. Look up the definition of the word converter also. These LED lights use inverters, the mains is rectified, converted to AC and fed to the LED diodes which conduct on one polarity and an anti-parallel diode conducts in the other.

As toroids are used for the majority of small inverter applications, for reasons you may or not be aware of, will have creapage and clearence distance greater than can be achieved with an iron cored transformer. But you also need good layout practises.

As with all standards, some manufacturers comply, some don't and some are criminal. A major european manufacturer, VW, comes to mind as does the fire death trap Vauxhall Zafera.

To tar all Chinese electronics manufacturers with the same brush is fatuous and scaremongering.

As to being fatuous, take a trip to Savoy Place and search the index in the library journal reference, don't use the online version, it does notgo back far enough. I think the argument about 2 pin non fused plugs was raging in the 1960 and 1970s

Malcolm

It makes sense to keep conductive materials away, but where do you think Ikea electronic products are made ? And they don't use transformers anymore because of the cost of the copper, they use an electronic inverter just like the lamp and they are made in mainland China too The electronic inverter has inheriently better isolation between input and output.

As they are double insulated an RCD will offer little protection in the case of an internal short Protect the wiring by using a 3A fuse, which incidently neither USA or Europe 2 pin plugs are fused. So fit a UK 13A plug and 3A fuse.

You can buy the identical unit from Amazon (UK) supplier for £7.99) or from the sewing machine distributors for £25

So yes, Caveat emptor, but do some research first.

Malcolm

Malcolm

As requested

http://www.ebay.co.uk/itm/321974937183?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

<http://www.ebay.co.uk/itm/321974937183?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT>

Malcolm

If you want a low cost solution to lghting for your machine and also to keep SWMBO happy, buy two of these magnetic base 30 LED sewing lights. One for her and one or more for youself. They are less than £5 on Ebay from China

I built the first of three and it works fine, About to do the video and started having eye troubles so everything was put on hold. I visited the hospital today and an operation is needed, but should not stop me from doing the video shortly, hopefully next week. The first unit controls a food mixer motor driving my wood lahe to be used for casting pattern making. The wood lathe dates back 50 years and is a Stanley Bridges wood lathe that was driven by a power drill. The second unit has an external electrically isolated heat sink to cater for the full 20 amp rating of the triac.

Photo of first unit showing the attachment of piggy back board to the first unit below.

Malcolm

Why pay over £10 when you can get the same functionality for £1.18

Malcolm

John

Forn the module I am using, search for item number 221904245698 on ebay. It says 4KW, but the heat sink is not big enough for that power. The traic is though, so for larger powers you could change the heatsink.

Malcolm

Give me chance to do the Youtube video, all will be revealed.

ICircuit was a screen grab, dots are the layout grid.

R5 & R6 100K, R7 15K, C3 10nF to 47nF dependent on motor characteristics. D1 & D2 1N4007. All other components as supplied on the dimmer.

A toner transfer PCB holds the components for the piggy back board with four leads between the boards.

I will post a image here of the PCB layout, see below

The ESR board is no better than the Hong Kong dimmers, as it does not have load compensating feedback.

Your are playing with leathal voltages, so be safe. Best to do test work with one of those Garden mower type ELCB modules that are designed to shut off the power when you mow the power lead.

The low cost dimmers from Hong Kong can hadle 2KW, cost about £1.18, I have a simple modification which adds a little piggy back board to give feedback. It senses the back EMF generated and uses that to compensate for the speed drop under load.

.R5, R6, R7 D1, D2 and C3 are the components that are added to the module. The module connections are changed and what was the input becomes the output and vise versa.

I will be adding a Youtube video of the process later this week.

Ketan

Good value, certainly. The Bisley H296NL-aa3 6 drawer unit is £123,60 inc VAT. Delivery extra. I can buy a lot of tooling for the £98,69 saving per drawer unit.

Malcolm

It seems there has been a design improvement which should improve the load carrying capacity.
Photos in my album, but I still can't add them to the message.

Edited By Malcolm Parker-Lisberg on 15/01/2016 14:04:59