Yes I have found some articles but all I have found are CCSs that can deliver 100mA and lower. Some on the tubes forum are really great but all of them are at least 100mA....
Hope, EC8010 will help over here. 🙁 As he said before, the circuit needs "a complete redesign and making it considerably more complex".
Don't know what will happen if I'll use bigger transistors than the MJE340 and BC558.... I need some reading.....
As I saw in the data book BC558 can deliver only 100mA.
By the way, I found in my "closet" a 2*12V transformer. I'll use it as a 24V for the Vac. Hope it 'll work..... more in a few minutes!
Hope, EC8010 will help over here. 🙁 As he said before, the circuit needs "a complete redesign and making it considerably more complex".
Don't know what will happen if I'll use bigger transistors than the MJE340 and BC558.... I need some reading.....
As I saw in the data book BC558 can deliver only 100mA.
By the way, I found in my "closet" a 2*12V transformer. I'll use it as a 24V for the Vac. Hope it 'll work..... more in a few minutes!
Hi resident,
The concepts are the same for larger values of current. The dissipation quickly becomes a problem though. A commercial example of what you are looking for in one form is called an "electronic load".
At higher currents you need to start using other methods to get good stable performance than a reference - transistor - resistor type set up.
-Chris
The concepts are the same for larger values of current. The dissipation quickly becomes a problem though. A commercial example of what you are looking for in one form is called an "electronic load".
At higher currents you need to start using other methods to get good stable performance than a reference - transistor - resistor type set up.
-Chris
wow! I did a google & ebay search and electronic loads are too expensive! And the most of them are too big for me!
What I didn't understand is that all of them has dc voltage and current ratings. What happened with AC voltages?
Because in my purpose I'll apply an AC voltage too. They don't have a problem with AC voltages? Sorry for my newbiness
What I didn't understand is that all of them has dc voltage and current ratings. What happened with AC voltages?
Because in my purpose I'll apply an AC voltage too. They don't have a problem with AC voltages? Sorry for my newbiness
Hi resident,
As long as the voltage on your DC CCS exceeds the peak AC voltage by a comfortable margin(compliance voltage), you will be okay. Also, the AC current should be less than the DC current through the CCS. You have your DC blocking capacitor (Don't forget to null out it's effect) so you should be good. The AC signal should look like a modulated DC waveform across the coil or transformer.
Yes, they are expensive. They are normally used to test power supplies, and so they sink current. Big heat sinks with many power transistors on them. The unit only has to provide ample base drive.
-Chris
As long as the voltage on your DC CCS exceeds the peak AC voltage by a comfortable margin(compliance voltage), you will be okay. Also, the AC current should be less than the DC current through the CCS. You have your DC blocking capacitor (Don't forget to null out it's effect) so you should be good. The AC signal should look like a modulated DC waveform across the coil or transformer.
Yes, they are expensive. They are normally used to test power supplies, and so they sink current. Big heat sinks with many power transistors on them. The unit only has to provide ample base drive.
-Chris
Finally one of the simplest circuits in the world just worked!
And I measured the first choke! And it's around 5H @ 100mA.
Don't know what happened but it's supposed to be 20H/200mA. But maybe I don't remember well. I have it for a long time now and there's nothing written on it.... so who knows.
The circuit works with:
Vdc(CCS) = 70Vdc
Vac = 24Vac (finally I used a toroid with 2*12V)
I have done two measurements. One with 50mA applied to choke and one with 100mA. At the first experiment is calculated as 5.8H and at the second as 4.9H
chris,
can you use an e-load as an AC load?
For example testing the secondary of a 6.3V transformer?
And I measured the first choke! And it's around 5H @ 100mA.
Don't know what happened but it's supposed to be 20H/200mA. But maybe I don't remember well. I have it for a long time now and there's nothing written on it.... so who knows.
The circuit works with:
Vdc(CCS) = 70Vdc
Vac = 24Vac (finally I used a toroid with 2*12V)
I have done two measurements. One with 50mA applied to choke and one with 100mA. At the first experiment is calculated as 5.8H and at the second as 4.9H
chris,
can you use an e-load as an AC load?
For example testing the secondary of a 6.3V transformer?
Hi resident,
-Chris
It might work as long as you put it "inside" a bridge rectifier. You will have a 1 ~ 1.5 VDC deadband due to the diode drops. Arrange the load so it's "+" goes to the "+" on the bridge rectifier, the negative goes to the negative terminal.
-Chris
Hi resident,
That is a good unit. You could make your own, but this is cheaper once you consider everything.
-Chris
That is a good unit. You could make your own, but this is cheaper once you consider everything.
-Chris
Just for information.
Filter Choke Analyzer
http://www.angelfire.com/electronic/funwithtubes/Filter_Choke_Analyzer.html
Filter Choke Analyzer
http://www.angelfire.com/electronic/funwithtubes/Filter_Choke_Analyzer.html
.....a diy project? That's great!
I think it is something like the previous example (or the same? ) from Radio Designer's Handbook that is posted before....
I'm reading the article now. More soon.....
I'm reading the article now. More soon.....
oups! One question that crossed my mind when reading the article...
I measured my choke with an AC voltage at 50Hz but the choke is designed to work at 120Hz. Doesn't this mean that this will give me a different value?
As I remember this choke is rated at 20H/200mA.....
I expected at 50mA I'll have much more than 20H.
I measured my choke with an AC voltage at 50Hz but the choke is designed to work at 120Hz. Doesn't this mean that this will give me a different value?
As I remember this choke is rated at 20H/200mA.....
I expected at 50mA I'll have much more than 20H.
resident said:
I'll see what I can do, but I'm a bit busy right now and have an awful lot of homework to do.
resident said:Am I missing something?
No, but they might be. It's a Tenma LCR meter. Digital bridges have a reputation for giving the wrong answer. Having said that, our Digimess 0.1% bridge seems to be quite good with everything I throw at it - as good as the Marconi TF2700!
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