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Τετάρτη, 19 Νοεμβρίου 2014

My first small Tesla coil with NE555 and flyback transformer.

This is my first Tesla coil.It's not completed yet actually.

Now all I need is to produce constant sparks off the top of the coil without touching a screwdriver or a lamp! I've tried some aluminum foil on top of the coil but nothing happens.How can that be done?A spark off the top without touching anything?Any suggestions?

Here I've used two separate power supplies-a 6V powering the NE555 and a 12V powering the 2N3055 and the flyback.I've also used a COSMO 1010 (C1010) photocoupler to make sure that the NE555 doesnt blow from the 12volt supply.

the coil
The secondary coil has about 400 turns of 0.4mm magnet wire wrapped around a 3cm paper roll.The primary is 5 turns of speaker wire.

capacitor bank
Here are the capacitors I've used:532J, 474J, .27J , .64J, .22J, 105J,124J, 822J/1.6KV.Most of the other caps are rated 400Volts I think.One or two 200Volts.

So ,if my calculations are correct then the bank should be about 4KVolts and 900 pFs.Or not.Maybe the bank is not good enough for spark on top.Maybe the bank is the culprit.

How to get the constant spark on top?

I know it has something to to do with resonance.Obviously there is no resonance here.
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Κυριακή, 16 Νοεμβρίου 2014

Σάββατο, 15 Νοεμβρίου 2014

12Volt/1Amp DIY power supply!

I've recently built a very simple 12V/1A power supply using a UA7812 and very basic components. It powers my DIY speaker containing a TDA2003 amp pretty well !

Here is the components I've used :

-a 20v transformer (this one I got from an old casette player)
-Four diodes for the rectifier.Mine are big ones but anyone from 2N4001-2N4007 will do.
-A 2700uF electrolytic capacitor placed after the rectifier bridge.
-a UA7812 transistor.You can also use an LM7812 or any other 7812 transistor.
-a 100nF film capacitor to dump the high frequencies to ground.It is connected from the output of the transistor to ground.

You can leave out the metallic box I've used from a broken supply.
This is a very basic power supply circuit with the minimum of components.
And that's about it.

Here is the schematic.
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Παρασκευή, 14 Νοεμβρίου 2014

Easiest circuit for begginers in electronics-Lighting a LED!

Here is a great and very simple circuit for beginners in electronics that lights a LED lamp!

All you need is a LED,a battery and a resistor

If you don't know which LED leg is positive and which is negative there is a very easy way to find out.

Look into the LED-the big lead is negative (Ground) .Ground connection always have to be bigger.Many problems arise in circuits because of bad grounding.

Here is a blow-up of a LED head.

the big lead is negative

Some science
Now let's go into some more detail.You need a resistor to light the LED and to protect it from excessive current.

resistor value
How to calculate the resistor value.

Simple.Using Ohm's Law V=IR or R=V/I.
An extended form would be R=V1-V2/I.

or resistance=sourceVoltage -LEDvoltage/LEDcurrent

Red LEDs have about 2 volts and their forward current is 15 miliAmperes or 0.015 Amperes.Other LED colors are rated different.

The battery we use here is 9 Volts.

So ,replacing the formula for these values we get

R=9V-2V/0.015=466.66667 or 467 ohms for the resistor.If you cannot find a resistor of the exact value then pick one with the next closest value.It will do.

resistor Wattage
Now we need the resistor Wattage.
ResistorWattage=sourceVoltage -LEDvoltage x LEDcurrent
R=9V-2Vx0.015=0.105 which means that 1/4 watt resistor will do.

Resistors come in various wattages 1/4, 1/, 1/2,1 watt,2,5,etc...

If you still cannot get it try this online Ohm's Law resistor calculator.
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Σάββατο, 1 Νοεμβρίου 2014

How I fixed a blown blender (thermal fuse).

Recently my neighbour brought a blown blender.It did not have power at all.So ,I opened it up to have a closer look inside.There are not much parts it the blender-some diodes and capacitors.I checked for continuity and power in various places and nothing seemed to be wrong.I got power right to the windings of the DC motors.

Nothing seemed to be wrong.I thought it must be the motor.So,I decided to have a look inside and started unwrapping the yellow tape around the windigs.Fortunately ,I didn't to unwrapp much -just half a turn- and voila.

a thermal fuse on a transformer
There it was hidden under the transformers yellow tape a THERMAL FUSE.I checked for power right before the fuse and it was ok-240Volts.Then I did the same after the fuse and I got zero power.I figured if I shorted the two ends of the fuse the motor should start.I took a small screwdriver and shorted the two ends and gues what-the motor kicked!

This little thing called a thermal fuse was the culprit.I did not have this kind of fuse to replace it and I used an ordinary 250V,5amp fuse for the time being until I get a proper thermal fuse.  

an ordinary 250V 5amp fuse

Nowadays most of the tranformers come with a thermal fuse.The problem is that sometimes they hide the fuse under the windings and you have to take the transformer apart in which case you're...screwed.

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Τι σημαίνουν οι ενδείξεις των ελαστικών.

Όλα τα ελαστικά των οχημάτων αναγράφουν στο πλαϊνό τους τμήμα μια πλειάδα από αριθμούς και κωδικούς, τα οποία δείχνουν τις διαστάσεις, τις προδιαγραφές του ελαστικού την ημερομηνία παραγωγής κ.ο.κ. Ας δούμε λοιπόν ένα – ένα αναλυτικά τι σημαίνουν τα... ιερογλυφικά των ελαστικών. Παράλληλα για να δείτε τους τύπους των ελαστικών αλλά και τι σημαίνει η ειδική σήμανση - ετικέτα πατήστε εδώ.
Παράδειγμα: 165/65 R14
Το 165 σημαίνει το φάρδος του ελαστικού σε χιλιοστά, το 65 είναι η σχέση ύψους προς φάρδος διατομής (65%), R σημαίνει δομή (Radial) και το 14 είναι η διάμετρος της ζάντας σε ίντσες.
Δείκτης φορτίου και πίεση αέρα
Στην φωτογραφία αναγράφεται μέγιστο βάρος ελαστικού στα 437 κιλά (ή 963 λίβρες) και μέγιστη πίεση στα 51 PSI ή 350 kPa.
Ημερομηνία κατασκευής
Ο τετραψήφιος αριθμός της φωτογραφίας υποδηλώνει την ημερομηνία κατασκευής του ελαστικού. Δηλαδή: Το 3612 σημαίνει ότι το ελαστικό κατασκευάστηκε την 36η εβδομάδα του 2012.
Δείκτης ταχύτητας
Στην εικονιζόμενη ένδειξη 79Τ, τα νούμερα αντιστοιχούν με το δείκτη φορτίου (το 79 αντιστοιχεί με 437 κιλά) και το γράμμα με το δείκτη ταχύτητας. Πιο αναλυτικά:
  • L έως 120 χλμ./ώρα
  • M έως 130 χλμ./ώρα
  • N έως 140 χλμ./ώρα
  • P έως 150 χλμ./ώρα
  • Q έως 160 χλμ./ώρα
  • R έως 170 χλμ./ώρα
  • S έως 180 χλμ./ώρα
  • T έως 190 χλμ./ώρα
  • U έως 200 χλμ./ώρα
  • H έως 210 χλμ./ώρα
  • V έως 240 χλμ./ώρα
  • W έως 270 χλμ./ώρα
  • Y έως 300 χλμ./ώρα
  • ZR > 240 χλμ./ώρα
Κωδικός έγκρισης
Ε2:  Ένδειξη συμμόρφωσης με κανονισμούς της ΕΕ. Ο αριθμός στον κύκλο μετά το E δείχνει τη χώρα έγκρισης.
Tubeless Radial
Tubeless σημαίνει χωρίς αεροθάλαμο (κοινώς σαμπρέλα) και Radial σημαίνει ότι ο κορμός αποτελείται από ακτινικές χορδές λινών. Αυτές οι χορδές είναι στρώματα υφάσματος που συγκροτούν τον κορμό του ελαστικού, και αναπτύσσονται ακτινικά κατά πλάτος του ελαστικού από τη μία στεφάνη στην άλλη.
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Δευτέρα, 20 Οκτωβρίου 2014

2n3055 transistor pinout

I always get a hard time finding the pinouts of various electronic components.I google their part name and I often get some very confusing results.So,I decided to keep to my own pinout images and files.

The 2N3055 is classified as a power transistor.

Here is the pinout

And here is the datasheet of 2N3055.

And some more datasheets.
Read more ...
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