BD139 Alternate replacement or surface mounted? help
Hello everyone. So recently I've been interested in learning more about inductive coupling. A wireless power circuit I'm trying to build calls for a transistor (BD139 in particular). I am salvaging the parts I need for this project as for I am not able to order or go buy parts atm. My main question is, is there a replacement for the BD139 that would meet the same parameters as this transistor? Providing surface mount equivalent would be better but full size is fine also.
maybe I'm being lazy but in my mind asking is the most logical choice. I read and learn, often I have to break my concentration on my study material so I can go study a related subject before I can continue what I was studying. I have a decent understanding of how transistors work.
thanks in advance
maybe I'm being lazy but in my mind asking is the most logical choice. I read and learn, often I have to break my concentration on my study material so I can go study a related subject before I can continue what I was studying. I have a decent understanding of how transistors work.
thanks in advance
Comments
The only reason I want to build this is so I can study it's design and make my own wireless power circuit but I need to fully understand how it works and for the most I do. However not fully and the value of the parts is what I'm more interested in.
I do so many things in and out of the world of electronics and its all just too much to try and retain so I try and skip remembering things that won't have a repetitive use or reference.
So im not sure about the working of a mosfet (I wanna say I learned about that years ago). If i remember correctly its a logic switch right?
Since it uses a 9V battery you may as well use a 2N2222 or similar (only the Vceo is important here really). Goodness knows which ark they got this circuit from. Expect the results to be very poor, you will need to have the windings very close together and poor efficiency.
I have been working on building coils using different material and methods but have no way to test.
So my next question is do you have a good idea of direction to point me in for learning more about this?
All of the examples I see online either are fake videos (The concept on which they build the circuit is not valid-guessing they make the videos for likes), or nice circuits with lack of explanation and what seems to be the most annoying is people are taking apart the QI standard chargers and putting the parts in other devices. That is not MAIKING your OWN wireless charging circuit, furthermore when I look into the QI chargers build construction and operation I noticed that there must be some handshaking going on and continuously but idk- its not a simple give and take, there definitely seems to be some conformation of information before the circuit kicks into full power. However there is some power present and I know because I tested it with a toothbrush-I don't have ANY lab items to dig deeper.
Anyway any help or direction would be great, I have no need or want for my circuit to transmit any information. I appreciate any help. thank you
doesn't need a second primary winding.
When you have a microcontroller in play there's a lot of scope for monitoring things like current voltage and power and
doing things like auto-switch-off, adjusting oscillation for maximum efficiency/resonance.
Using an old BJT as an free-running oscillator is ancient tech these days, kind of archeology
One thing to get right is the quality of the tank circuit capacitor and inductor - they need to be low loss as
they will be resonant to get good energy transfer to the secondary, which means you want quality plastic film
capacitors and low resistance in the coils (litz wire is often used). That way you get most of the power into the
receiving circuit, not heating the capacitor or coils. You have to exclude any iron or steel parts from the
vicinity of the coils too, they will soak all the power as eddy current losses.