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ZHIYU ZPB30A1  while this is original developer of  60W and 110W and proof this is that they are capable of firmware developing.
Some one from a near by village in China acted as copycat at 60W model, and now this copied product gets marketed as TX6880DH.

I am professional electrician and I have no faith to any copycat design, especially speaking of electrical specifications.

ZPB30A1 product design comes with relaxed electrical specifications speaking of accuracy, and I do laugh when hobbyists trying to verify accuracy by using all sort of trash digital voltmeters 5$ worth at eBay,  or by them using multimeter of 20$ retail.

Bellow there is a picture which I composed by my self, and here it is pictured, best quality of Male BNC plug to banana terminals from Asia.

Unfortunately eBay this is now full such parts made by iron and painted with cheap paint.

I do own two of such converters and now I need another two of identical quality.
I have a four-wires measuring equipment with BNC plugs and I am up to using also new cables with banana plugs and compatible Kelvin clips.

Mission: ;)
Four of those converters will aloud connection points for four banana plugs, at their positive marked side.

Warning: I consider cheap fake copies as extreme risk because damage of high-quality female BNC plugs (over the equipment panel) this is expected to happen.
BNC center pin this not machined under any mechanical specification (dimensions standard) this is major enemy.

Unfortunately Taiwanese factory making quality accessories looks as hidden, your only way to identify the good-ones this is due pictures.
Electric Motor connected with dimmer becomes a sound speaker of High pitched noise.

Summer heat this is too much in Greece starting from hart of June and up to 10 of September.
At home I have one large (old school) Mitsubishi electric fan,  it is great to keep you cool at midday time but at nights it is impossible for you to sleep near it.
This is desktop fan, full metal, blades diameter close to 60 centimeters.

And I did use as experiment one lights dimmer (by foot adjust type / sliding potentiometer), I connected to it one female power socket ( for cables extension), and I thought that I am good to go.  ;D   :P

By starting using it and adjusting the speed, the motor  this become instantly a sound speaker of High pitched noise  ::)
My plan to slow down the electric fan rpm this was successful,  but this  High pitched noise it is something that no human can tolerate.

Light bulbs can tolerate using dirty energy but regular electric motors are not prepared for a such conditions.

In conclusion: 
Noiseless speed control for Mains volts this is a job for variac transformer and of nothing else.  ;)

bench-top grinding wheel (power tool), this is a must have for most maintenance electricians, and for many others.

This topic it is dedicated to maintenance of grinding wheel stones.

While selection of grid for its rotating stone this is a matter of choice, most people will agree to similar grid for the stone this removes large particles.
Second choice and far more important this is selection of stone for medium or fine work (higher or highest grid).

I work mainly with metals as soft iron, copper, aluminum, and also with transparent materials as is Plexiglas, acrylic plastics and plastics.
Recently I made a choice for a 420 grid (grinding wheel stone) this is by made by TYROLIT (green color) and new production item.
My new problem to solve this is that in such of fine grid,  particles of Plexiglas & acrylic plastics and plastics, they have the tendency to melt and such sticky particles they pollute grinding surface of the stone.

Professional users of bench-top grinding wheels, they never have just one machine, and they always use with respect to stone wheel only friendly materials to it ( closest to wheel stone handling specifications).

I have only one machine of professional grade of bench-top grinding wheels, therefore I am forced to work with several different materials and only two stones.

In the Market   
There is a rather inexpensive tool this is metal coated with diamonds, this helping stones to restore their surface by removal of grinding material.

Now there is a catch (fine detail),  such Diamond coated Dressing tools, they are not all alike.
There is a separation in the regard of grid number.

Most ones with lowest price this is for very low grid and totally unfriendly to use with stones of high grid.
At economy priced Dressing tools,  you need to identify grid by looking the pictures.
Higher density of diamond particles over metal this translates to medium grid.  

Also there is out there and tools for Fine Grid, they are priced higher than other grids, and selection this is also tricky.
If Fine Grid tool this is finest that your stone grid, them your stone grid number will become higher even temporarily.

I am not after scarpering knifes,  but I need flat surface as sides of rather soft metals and plastics.
Such work is possible with medium grid stones and fine grid stones, if you work at fine grid stones with more patience.

In conclusion ....
Instead buying three of Diamond coated Dressing tools, you might solve the problem by getting one for medium grid.
At eBay jungle this is priced of 2.50EUR and higher ( I did ultra long research) , but you also need to inspect product pictures carefully.
If a seller using product pictures illustrating several but different tools and single price = avoid him.     
New update after 2 years and 5 months in Use.

I made today internal resistance measurements of four from eight batteries.
News are so and so.
Batteries when-new they did measure 19 to 20 milliohm its one.

Now batteries started aging and internal resistance this increased but differently from cell to cell, and imagine that those cells operate always as team of four.
This translates that any amount of use or abuse, this is equal to all.

According to my own batteries naming:
M8 = 28 Milli ohm     
M7 = 29 Milli ohm
M6 = 22 Milli ohm
M5 = 24 Milli ohm

Measurement was taken with cells fully charged.

Now according my experiences so at about 45 Milli ohm its cell would have lost 50% of capacity.
While arrival of my load PCB this can take several days, I am feeling allot of enthusiasm about this project !

In my planning this is to create one high quality enclosure for this PCB, and professional grade cables and connectors for it.
For example I just discovered one pair of Kelvin type clips designed for battery Lead Acid, this usable for very small ( 7Ah ) up to larger ones.
And interestingly enough front jaws design, are flat and look good even for LCR use and even components testing.

With such clips at hand, I will make one foolproof set of cables, this will use 4 wires connectivity, and will be 100% safe regarding short circuit accidents.

I liked them that much and got three pairs.  8)

Speaking of output connections :
No rule forbids having in your enclosure in parallel connections of  both.
Banana binding post ( 2 x 20A & 2 x 5A female (voltage sense) ) among with 4Pin Male & Female Panel Chassis ( for  battery type Kelvin clips ) 
Here I am starting to explore LED display components.

Three digits LED this is SP420361N   1534   0.56 inch

Four digits LED this is SR420361N 1549


The all idea, this is if I can find compatible with a larger dimensions this to be replaced.
For DIY printed labels I just discovered A4 Self Adhesive Glossy Photo Inkjet Paper.

I did order some so to try it.


It comes with hard to believe specifications: Anti Smudge and Water Resistant
New PSU this is now tested and ready for delivery.  :)
My own friend and customer he did fall in love with it, design and quality far from his own expectations. 8)

My first ever made one, I did it at age of 21 years old, with minimum use of specialized tools.
If recent version this looking significantly better as build, this is due advanced craftsmanship skills, that no copycat can have or buy.

Last pictures:
a) New 20Kg of electrical power
b) The artist ... with 30 Celsius indoor at night.  ;) (June 23 2017)

HIOKI RM3542A Resistance Meter this is a tool that I am aware that with out it I would be blind in the world of resistors.  ;)

Recently I made a power supply for a friend with eight power transistors connected in parallel.
Therefore I was forced to buy several 5W 0.1R ( we called them as cement type) in Greece.
By having around HIOKI RM3542A this become a great opportunity to actually measure and make a conclusion of specific resistors tolerance by %, as this is usually not labeled any more.
In past two decades most such resistors were  labeled as 5% or 10%.

Twenty years later that manufacturing technology supposedly become more precise, now they do not label in full such resistors.

Now lets see what I got speaking of measurements of twelve resistors.

HIOKI RM3542A set at measuring range of 100 milliohm , and comparator system set at 1% (+/_)

Resistor value  ......  comparator  Value
99.1073  ....   - 0.983
99.0805  ....   - 0.919
100.2165 ....  + 0.226
99.5548  ....   - 0.455

97.9256  ....  - 2.074
100.0870 .... + 0.087
99.2508   ....  - 0.749
97.6602  ....  - 2.340

100.0140 ....  + 0.014
98.1107  ....  -  1.889
99.9268  ....  - 0.073
99.7705  ....  - 0.229 

I do not know how to react speaking of conclusion.
Should I be happy ? That this factory aiming for  0.5% tolerance on average.
Should I get mad ?  Because production quality this is far from be stable.

Another mystery with specific resistors this is their wattage, version of 22 Ohm resistors from this factory was unable to tolerate equal wattage with resistors made at 90s,  and new resistors got up to 100 Celsius right away, and due wattage limitation they caused huge output voltage sag over load condition.

New resistors was indeed selected to match actual transistor specifications, and they do not get hot at all.

My thoughts now are that precision in resistance manufacturing this also influenced wattage, and this also become more precise,  this now translates that hobbyist makers are in higher risk of watching resistors to get in flames,  when they will do wrong parts selection.

Professional electronics engineers they have modern tools, and parts selection will be precise.
And in case that an electronic part this fails, then it is a manufacturer fault.

Within 2017 precision this is all around us.
And your measuring gear this must be equally precise according to electronic spare parts that you are going to work with.
Low Ohm measurements this is a job for measuring equipment which they have lower measuring range, this be close to measuring value.

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