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Author Topic: Oscillator Powering 6 Modified Led bulbs  (Read 62310 times)

magnetman12003

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #45 on: May 09, 2017, 03:22:35 AM »
The voltage of any neon you get, will be dependent upon which transistor you are using, if you are using a 100 volt transistor, then a 100 volt neon would be good.
So, a higher voltage transistor would be best in these types of radiant spike circuits and in case you forget to connect the load for some reason, high voltage would be present across the transistor.
peace love light
Do you think a C4423 transistor could be used in place of the TIP3055 transistor in the 12 volt circuit.  It has a voltage rating of 400 volts and 10 amps.  How about a BUH1015  which has a voltage rating of 700 volts?   I have lots of each.

SkyWatcher123

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #46 on: May 09, 2017, 05:17:56 AM »
Hi magnetman, that would be a good choice, it would be safety margin and would be more reliable.
If anyone is going to use these light circuits while they are away, i would also add a fuse of proper rating.
peace love light

magnetman12003

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #47 on: May 09, 2017, 07:17:02 AM »
Hi magnetman, that would be a good choice, it would be safety margin and would be more reliable.
If anyone is going to use these light circuits while they are away, i would also add a fuse of proper rating.
peace love light
[/quote

Do you have an idea what base resistor value is needed-watts also. if I use a BUH1015 transistor instead of a TIP3055 in your 12 volt circuit?
The BUH1015 is used in the horizontal output section of a TV.  Very fast switching large transistor. Shown is my monster ferrite ring compared to a lemon. If I don't use it I will sell it. Its already been taped Coil winding comes next.

gyulasun

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #48 on: May 09, 2017, 12:51:20 PM »
....
Do you have an idea what base resistor value is needed-watts also. if I use a BUH1015 transistor instead of a TIP3055 in your 12 volt circuit?
The BUH1015 is used in the horizontal output section of a TV.  Very fast switching large transistor. Shown is my monster ferrite ring compared to a lemon. If I don't use it I will sell it. Its already been taped Coil winding comes next.

Hi magnetman,

Here is a data sheet for your transistor: http://pdf.datasheetcatalog.com/datasheets/105/365081_DS.pdf 
and the parameter  hFE  (DC current gain) is shown to be between 7 to 14 only (page 2, in the middle of tabelle Electrical Characteristics).   This means that to have a collector current of say 100 mA, you need to pump roughly 100mA/10mA=10mA base current via a resistor from the supply (I considered the typical  hFE = 10 from data sheet, and hFE = IC/IB 
Now to provide 10 mA base current, you would need to use a resistor which provides this from your input supply voltage. IF you use 5V DC input, then base resistor R could be  (5V-0.8V)/10mA = 420 Ohm or if you use 12V then R=(12V-0.8V)/10mA = 1120 Ohm. (The 0.8V I considered is the forward bias voltage drop between the base and the emitter.)
The power dissipation in such resistor may be evaluated too,  base current squared times the resistor, i.e.  .01A*.01A*1120 Ohm= 112 mW  or for a 420 Ohm at 5V DC supply it would be 42 mW.

Of course this is an approach in theory but can still serve to get an insight, the AC feedback voltage transformed back from the collector winding via the coupling coil to the base will modify the base current. 

A good approach in practice would be to use a 100 Ohm  3 W resistor in series with a 1 kOhm potmeter rated for also at least 2W or higher.  This is not an overkill but precaution because making the base current adjustable is always advisable to find a "sweet" operating point for the transistor and if you happen to bring the wiper of the potmeter to zero Ohm during the tests then the base current would increase to 112 mA via the series 100 Ohm from a 12V supply voltage and then the dissipation in the 100 Ohm would increase to 1.25 W.

Gyula

magnetman12003

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #49 on: May 09, 2017, 09:26:10 PM »
Hi magnetman,

Here is a data sheet for your transistor: http://pdf.datasheetcatalog.com/datasheets/105/365081_DS.pdf 
and the parameter  hFE  (DC current gain) is shown to be between 7 to 14 only (page 2, in the middle of tabelle Electrical Characteristics).   This means that to have a collector current of say 100 mA, you need to pump roughly 100mA/10mA=10mA base current via a resistor from the supply (I considered the typical  hFE = 10 from data sheet, and hFE = IC/IB 
Now to provide 10 mA base current, you would need to use a resistor which provides this from your input supply voltage. IF you use 5V DC input, then base resistor R could be  (5V-0.8V)/10mA = 420 Ohm or if you use 12V then R=(12V-0.8V)/10mA = 1120 Ohm. (The 0.8V I considered is the forward bias voltage drop between the base and the emitter.)
The power dissipation in such resistor may be evaluated too,  base current squared times the resistor, i.e.  .01A*.01A*1120 Ohm= 112 mW  or for a 420 Ohm at 5V DC supply it would be 42 mW.

Of course this is an approach in theory but can still serve to get an insight, the AC feedback voltage transformed back from the collector winding via the coupling coil to the base will modify the base current. 

A good approach in practice would be to use a 100 Ohm  3 W resistor in series with a 1 kOhm potmeter rated for also at least 2W or higher.  This is not an overkill but precaution because making the base current adjustable is always advisable to find a "sweet" operating point for the transistor and if you happen to bring the wiper of the potmeter to zero Ohm during the tests then the base current would increase to 112 mA via the series 100 Ohm from a 12V supply voltage and then the dissipation in the 100 Ohm would increase to 1.25 W.

Gyula


Thank you much for your input help on this Gyula.  I am not familiar how to use the transistor tables at all. I need now is the resistor since I already have the 1k pot, transistor,cap and diode

gyulasun

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #50 on: May 09, 2017, 09:40:26 PM »
Well, you can use any resistors in series, if you have some say 56 or 82 or 120 Ohm, not critical.

magnetman12003

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #51 on: May 09, 2017, 09:45:35 PM »
I have a question about using this type of power supply shown below.  The rating is 20 amps. The power supply has TWIN DC terminals.  Does that indicate I can only draw 10 amps off one dc terminal and 10 amps off the other dc terminal??  Or can I draw 20 amps off only one of the terminals?

No answers from the seller so far.

gyulasun

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #52 on: May 09, 2017, 09:58:33 PM »
Well if you can see three  COM and three V+ labels above the terminal strip like on this power supply I chose at random:
http://www.ebay.com/itm/191696481796 

then it means you can draw 20A from any one COM and one V+, ok?   The three COM terminals next to each other are the same negative polarity and the three V+ terminals are the same positive polarity outputs.  The expalanation for having 3 of them each is to increase connect surface area. No restriction for 10A or whatever.

magnetman12003

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #53 on: May 09, 2017, 10:36:49 PM »
Well if you can see three  COM and three V+ labels above the terminal strip like on this power supply I chose at random:
http://www.ebay.com/itm/191696481796 

then it means you can draw 20A from any one COM and one V+, ok?   The three COM terminals next to each other are the same negative polarity and the three V+ terminals are the same positive polarity outputs.  The expalanation for having 3 of them each is to increase connect surface area. No restriction for 10A or whatever.
[/quote

Thanks for the explanation.  I have one on order and did not want to damage it later on.

Naija

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #54 on: May 10, 2017, 02:53:03 AM »
Hello Skywatcher,

Will your circuit drive 7w 220V led bulbs or was it specifically designed for 40w led bulbs? Am thinking that having several multiples of 7w 220V led bulbs is better suited to my replication of your circuit.

SkyWatcher123

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #55 on: May 10, 2017, 06:22:33 AM »
Hi Naija, i chose the 5.5 watt- 40 watt equivalent led bulbs, to get a better intensity or brightness from the bulbs.
For your 220 volt bulbs, you might need to use more turns, maybe an extra coil layer, maybe not, experiment will tell you this.
It may be that the 220 volt led bulbs, could give more efficiency with this type of setup, i don't have any 220 volt versions on hand, so i don't know.
This i can tell you, the multiple led bulb in parallel approach, run off this type of circuit, is more than just spreading the light around.
The radiant spikes from the oscillator are being converted very efficiently by the buffer capacitor and whatever passes by that and into the multiple bulbs, to give far more lumens than one would expect for the wattage input.
Are we getting benefit from placing multiple bulbs spaced apart, of course, but that is not the whole story, just part of it.
peace love light

Naija

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #56 on: May 10, 2017, 09:22:33 AM »
Hi Naija, i chose the 5.5 watt- 40 watt equivalent led bulbs, to get a better intensity or brightness from the bulbs.
For your 220 volt bulbs, you might need to use more turns, maybe an extra coil layer, maybe not, experiment will tell you this.
It may be that the 220 volt led bulbs, could give more efficiency with this type of setup, i don't have any 220 volt versions on hand, so i don't know.
This i can tell you, the multiple led bulb in parallel approach, run off this type of circuit, is more than just spreading the light around.
The radiant spikes from the oscillator are being converted very efficiently by the buffer capacitor and whatever passes by that and into the multiple bulbs, to give far more lumens than one would expect for the wattage input.
Are we getting benefit from placing multiple bulbs spaced apart, of course, but that is not the whole story, just part of it.
peace love light

Thank you Skywatcher for your answers and please one final one (hopefully), if I were to use 8 identical bulbs, there won't be need for an incorporated second circuit right? Which means only one transistor is required. If this were so, then which of the two transistors in your circuit should I use, the NPN or PNP?

Naija

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #57 on: May 10, 2017, 10:04:24 AM »
Hello Skywatcher, in your older circuit, you were using TIP3055 with only one neon bulb. Would you recommend me using the same transistor for the 8 identical bulbs in parallel?

gyulasun

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #58 on: May 10, 2017, 10:28:33 AM »
....
Here is the circuit drawing and a pic, just to give an idea.
....

Hi SkyWatcher,

I just noticed a drawing error in your circuit schematic: you mixed up the emitter and collector pins of the PNP transistor.
I have corrected the drawing, see it attached below.

Gyula

gyulasun

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Re: Oscillator Powering 6 Modified Led bulbs
« Reply #59 on: May 10, 2017, 06:19:18 PM »
Thank you Skywatcher for your answers and please one final one (hopefully), if I were to use 8 identical bulbs, there won't be need for an incorporated second circuit right? Which means only one transistor is required. If this were so, then which of the two transistors in your circuit should I use, the NPN or PNP?

Hi Naija,

Skywatcher will surely answer you,  let me give just a general piece of advice on transistor types:  basically what you would need is a high voltage rated fast switching transistor.  Such types are mainly NPN ones, preferably have low collector-emitter saturation voltage, VCEsat  and a relatively high hFE  Dc current gain, known also a Beta, Ic/Ib. 
These types are developed for switching mode power supplies or for electronic lamp ballast circuits.  If you cannot buy such types at your location, you may scavenge some from discarded PC power supplies, or 120V and 230V fluorescent light bulbs etc.

Here are some types, though you can surely find other types too, now that you know what to search.

Fairchild (now Onsemi) type FJP5554, see at Digikey, Farnel, RS Components, Mouser:

https://www.digikey.com/product-detail/en/fairchild-on-semiconductor/FJP5554TU/FJP5554TU-ND/1473889
400V 4A 70W, hFE is between 20 to 100, saturation voltage is max 0.5V at Ic=1A.

ST Microelectronics type BUL742C,  see at Mouser and Farnell,
http://eu.mouser.com/_/?Keyword=BUL742C   
400V, 4A, 30 or 70W, hFE is between 25 and 100, saturation voltage is typical 0.15V at Ic=1A.

Gyula