Hey Bill, I mentioned to you how to measure the maximum power from any battery source and determine it's output impedance. For a JT circuit you are now working with a discharging inductor, so it's a different story. An ideal discharging inductor has a theoretical output impedance of infinity. That means it doesn't matter what value of resistive load you connect to it, the inductor will raise it's output voltage enough to keep the current flowing at it's initial rate.
You can use that knowledge to make a very easy power output calculation for the JT. Just connect a bigish cap and a resistor in parallel as the load for the JT circuit. The pulsing inductor will charge the cap and the resistor will drain the cap. It will stabilize at a voltage were the average power out from the JT inductor will be dissipated in the resistor. So your JT output power is then V(cap)-squared/R.
Suppose you measure 10 volts when you use a 1K resistor. If you change the resistor to 2K then the cap voltage will stabilize at a higher voltage. When you do the calculation again, you should measure the same power. As long as the cap is big enough it will smooth out the inductor pulses. If you multiply R x C, you get units of seconds, the time constant. As long as the time constant is 10x longer than the JT pulse period you are fine, the voltage across the cap will be near DC.
The JT circuit has a fixed output power, independent of the load. That's in contrast to a battery power source were the output power from the battery is dependent on the type of load. So if you make the power calculation using the RC load, then reconnect an LED configuration, you will know how much power the LEDs are dissipating.
Thanks. The folks on our Joule Thief topic on overunitydot com have developed some amazing joule thief circuits and I need to replicate some of those to increase my output. This was just the most basic JT circuit so hopefully, there is room for improvement.
Thanks! I don't fully understand supercaps. what I do know from experience with them is, they can charge up fast and feed power back like a battery. Depending upon the load, and the Farad rating of the cap, they can last a good bit. I short the caps before my experiment and then, the earth batery appears to not only light the leds, in this case 7, but also charge the caps as evidenced by my bringing the breadboard inside and the leds were still lit for a bit. I am getting a 3,000 Farad cap.
The large supercap is made by Maxwell and is 3,000 Farad and 2.3 volts. Once charged up, I would think it will light stuff for a long time. It costs over $100.00 so I have to save up.
I should add that Nathan Stubblefield (Inventor of cell phones and the earth battery) illuminated his home, heated his home, powered the phone system of Murry, KY and ran his farm, all from his earth batteries. So, I guess this is possible as this was in the late 1900's.
Nathan Stubblefield! yeah i almost forgot about him Nikola Tesla visited him if i remember right! i am going to find a documentary on him tonight:)thanks!!!
Hey Bill, I mentioned to you how to measure the maximum power from any battery source and determine it's output impedance. For a JT circuit you are now working with a discharging inductor, so it's a different story. An ideal discharging inductor has a theoretical output impedance of infinity. That means it doesn't matter what value of resistive load you connect to it, the inductor will raise it's output voltage enough to keep the current flowing at it's initial rate.
Drevtoobe 2 years ago
You can use that knowledge to make a very easy power output calculation for the JT. Just connect a bigish cap and a resistor in parallel as the load for the JT circuit. The pulsing inductor will charge the cap and the resistor will drain the cap. It will stabilize at a voltage were the average power out from the JT inductor will be dissipated in the resistor. So your JT output power is then V(cap)-squared/R.
Drevtoobe 2 years ago
Suppose you measure 10 volts when you use a 1K resistor. If you change the resistor to 2K then the cap voltage will stabilize at a higher voltage. When you do the calculation again, you should measure the same power. As long as the cap is big enough it will smooth out the inductor pulses. If you multiply R x C, you get units of seconds, the time constant. As long as the time constant is 10x longer than the JT pulse period you are fine, the voltage across the cap will be near DC.
Drevtoobe 2 years ago
The JT circuit has a fixed output power, independent of the load. That's in contrast to a battery power source were the output power from the battery is dependent on the type of load. So if you make the power calculation using the RC load, then reconnect an LED configuration, you will know how much power the LEDs are dissipating.
Drevtoobe 2 years ago
Thats Great Bill running a JT off an earth battery.
GBluer 2 years ago
Thanks. The folks on our Joule Thief topic on overunitydot com have developed some amazing joule thief circuits and I need to replicate some of those to increase my output. This was just the most basic JT circuit so hopefully, there is room for improvement.
Bill
Pirate88179 2 years ago
Thank you. That is very good information to have. I will do my best to make these measurements and calculations. Thanks again.
Bill
Pirate88179 2 years ago
great job, five stars.
crob227 2 years ago
Thanks man, I appreciate that.
Bill
Pirate88179 2 years ago
7 lights already :) How long do the supercaps last? Can you charge them with the earth battery?
01Anastasia01 2 years ago
Thanks! I don't fully understand supercaps. what I do know from experience with them is, they can charge up fast and feed power back like a battery. Depending upon the load, and the Farad rating of the cap, they can last a good bit. I short the caps before my experiment and then, the earth batery appears to not only light the leds, in this case 7, but also charge the caps as evidenced by my bringing the breadboard inside and the leds were still lit for a bit. I am getting a 3,000 Farad cap.
Pirate88179 2 years ago
Man, that's insane....
3000 Farads!?! Is that even possible?
You don't wanna short that one out when fully charged, I'll bet the heat would destroy it ;D
Nabo00o 2 years ago
The large supercap is made by Maxwell and is 3,000 Farad and 2.3 volts. Once charged up, I would think it will light stuff for a long time. It costs over $100.00 so I have to save up.
Bill
Pirate88179 2 years ago
that is cool! maybe one day we can run a house from the earth!
eroutt 2 years ago
Thanks! I can't say now if that is possible but, I am a big believer in being able to scale things up. So, who knows?
Bill
Pirate88179 2 years ago
I should add that Nathan Stubblefield (Inventor of cell phones and the earth battery) illuminated his home, heated his home, powered the phone system of Murry, KY and ran his farm, all from his earth batteries. So, I guess this is possible as this was in the late 1900's.
Bill
Pirate88179 2 years ago
Opps, I meant late 1800's. Like around 1890.
Bill
Pirate88179 2 years ago
Nathan Stubblefield! yeah i almost forgot about him Nikola Tesla visited him if i remember right! i am going to find a documentary on him tonight:)thanks!!!
eroutt 2 years ago
Each LED has a forward volt draw of 3.5-4.5 volts and 30 mA's. This is for each one. I still think it will run more.
Bill
Pirate88179 2 years ago