3 months with no progress 😡
I have all the parts but I didn't build the jig. But now I'm back in action and I'm starting today.....
I have all the parts but I didn't build the jig. But now I'm back in action and I'm starting today.....
Any help with the value of the resistor at the base of the MJE and the value of the pot? 
Would it be better to use a larger transistor than the MJE350?
And one more question,
Would it be a problem if I'll use a simple filtering at the HT of the current source? Like a simple diode/bridge and a cap?
I'm planning to use a variac - bridge- 1 or more electrolytic caps so I can vary the HT voltage from a few volts to 100V easily.
Would it be better to use a larger transistor than the MJE350?
And one more question,
Would it be a problem if I'll use a simple filtering at the HT of the current source? Like a simple diode/bridge and a cap?
I'm planning to use a variac - bridge- 1 or more electrolytic caps so I can vary the HT voltage from a few volts to 100V easily.
The pot will have 1V across it, so if you wanted a maximum current of 100mA, it would need to go down to 10R (add a 10R fixed resistor in series with the pot) and if you wanted to vary current between100mA and 1mA, then 1mA would require 1k, so a 1k pot would do nicely.
The other resistor needs to ensure that you drive 5mA through the LEDs. Using a variac will make that a bit tricky. You could always use a smaller resistor and a 9V battery to power the LEDs.
The other resistor needs to ensure that you drive 5mA through the LEDs. Using a variac will make that a bit tricky. You could always use a smaller resistor and a 9V battery to power the LEDs.
Hi,
Just caught this thread, have not read it so far but this is so strange.. i obtained one of these from a skip at uni complete with manual not long ago.
I just installed a mains DC supply into it because the battery was leaking but all the guts are immaculate. It works very well for resistance but for L and C it tends to swing to one extremity and stay there no matter what range its on.
Anyway ill read the thread now and see if i can be of help 🙂
Just caught this thread, have not read it so far but this is so strange.. i obtained one of these from a skip at uni complete with manual not long ago.
I just installed a mains DC supply into it because the battery was leaking but all the guts are immaculate. It works very well for resistance but for L and C it tends to swing to one extremity and stay there no matter what range its on.
Anyway ill read the thread now and see if i can be of help 🙂
Thanks EC8010!
Graig the topic of the thread has been changed a little....
I don't know if I must start a new thread with a different subject or not. Like "a jig to measure iron-core chokes" or "how to measure a choke" or whatever.....
I leave this to the authors.
Graig the topic of the thread has been changed a little....
I don't know if I must start a new thread with a different subject or not. Like "a jig to measure iron-core chokes" or "how to measure a choke" or whatever.....
I leave this to the authors.
😀 The jig is ready!
Need to bring the second variac for the Vdc of the CCS.
I didn't find MJE350 with a TO-3P package and it's a little bit small!
And I put it on a standard "LM317" heatsink... Hope it will not get fried. I'll take care with the voltages and the ammount of current....
More soon.....
Need to bring the second variac for the Vdc of the CCS.
I didn't find MJE350 with a TO-3P package and it's a little bit small!
And I put it on a standard "LM317" heatsink... Hope it will not get fried. I'll take care with the voltages and the ammount of current....
More soon.....
out of topic:
I just bought an isolation transformer for my tinylab. Two variacs and too much cables around, I don't want to touch 220V and get fried!
It's a simple 220/220 transformer. The weird is that it's plugged in the wall socket with the secondary un-plugged (no load) and it dissipates some heat (I checked it by touching the core). Is this normal? 😕
I just bought an isolation transformer for my tinylab. Two variacs and too much cables around, I don't want to touch 220V and get fried!
It's a simple 220/220 transformer. The weird is that it's plugged in the wall socket with the secondary un-plugged (no load) and it dissipates some heat (I checked it by touching the core). Is this normal? 😕
the circuit doesn't work!The CCS worked fine until I put the AC voltage. Bridge of the CCS' PSU and LEDs got fried 😀
Don't know about the MJE and the BC yet.......
Hi Chris,
Yes I have installed it! The circuit was ok and the CCS worked fine!
Then, I burned it! 😀
I use two variacs, one for the Vdc and the other for the Vac (// choke)
The variacs are connected in the same multi-socket. And I have connected them out of phase. So the other variac was not at 0V when I was trying to connect it to the jig. But was carrying the phase!haha
So,
I put the variacs in phase but I didn't have other parts right now to check the jig. Tomorrow, I'll build it again.....
Yes I have installed it! The circuit was ok and the CCS worked fine!
Then, I burned it! 😀
I use two variacs, one for the Vdc and the other for the Vac (// choke)
The variacs are connected in the same multi-socket. And I have connected them out of phase. So the other variac was not at 0V when I was trying to connect it to the jig. But was carrying the phase!haha
So,
I put the variacs in phase but I didn't have other parts right now to check the jig. Tomorrow, I'll build it again.....
Resident,
I do not actually test chokes very often. I use the Hanna method for design of both chokes and OPT primaries and a very simple formula for general checking to see if the inductance I expect is available from a specific design. One of the nice things about Yves OPT calculator is he went to the trouble to provide the loss of impedance Vs lower frequency for OPT's.
The formula comes from the RDH4, which you can download here.
http://www.pmillett.com/technical_books_online.htm
without worry over copyright problems. Look at page 282 through 291 and use the formula from page 285 formula 3.
The permeability chart on page 284 will provide the incremental permeability Vs flux density, for the add on to that formula for gapped core. Also you should know that the minimum permeability for core types in common use is 350 for M6, 250 for M19 and 150 for M50. These are for 1 vac @ 120 Hz inductance bridges.
If you extend the main curve off of the page, which is for M3, in current metals production, you can actually work back to higher perms for the other three metals I gave you minimum values for. This is a very accurate formula, and you can fine tune it using your test fixture, for adding DC.
Bud
I do not actually test chokes very often. I use the Hanna method for design of both chokes and OPT primaries and a very simple formula for general checking to see if the inductance I expect is available from a specific design. One of the nice things about Yves OPT calculator is he went to the trouble to provide the loss of impedance Vs lower frequency for OPT's.
The formula comes from the RDH4, which you can download here.
http://www.pmillett.com/technical_books_online.htm
without worry over copyright problems. Look at page 282 through 291 and use the formula from page 285 formula 3.
The permeability chart on page 284 will provide the incremental permeability Vs flux density, for the add on to that formula for gapped core. Also you should know that the minimum permeability for core types in common use is 350 for M6, 250 for M19 and 150 for M50. These are for 1 vac @ 120 Hz inductance bridges.
If you extend the main curve off of the page, which is for M3, in current metals production, you can actually work back to higher perms for the other three metals I gave you minimum values for. This is a very accurate formula, and you can fine tune it using your test fixture, for adding DC.
Bud
Hi Bud!
Thanks for the info on calculating chokes. I allready have the book. I bought it used a few years ago... But haven't ever use Hanna's method. It was not in my plans to wind chokes I wanted to build the jig just for measure them in different values of mA. It's cool if you want to design a PSU using a 100mA choke at 50mA cause you have different value of Henry. I wanted to know how much the L would be of a choke from junk in my PSU designs....
But blindsjc at the other thread "woke up" my plans on building the winding machine!
One of my next projects will be a guitar amp, maybe a Showman clone, and it'll be interesting to wind the OPT (and the choke 😉 ) by my own!
I'll be following the thread........
Thanks again!
Thanks for the info on calculating chokes. I allready have the book. I bought it used a few years ago... But haven't ever use Hanna's method. It was not in my plans to wind chokes I wanted to build the jig just for measure them in different values of mA. It's cool if you want to design a PSU using a 100mA choke at 50mA cause you have different value of Henry. I wanted to know how much the L would be of a choke from junk in my PSU designs....
But blindsjc at the other thread "woke up" my plans on building the winding machine!
One of my next projects will be a guitar amp, maybe a Showman clone, and it'll be interesting to wind the OPT (and the choke 😉 ) by my own!
I'll be following the thread........
Thanks again!
Ok, I have built the CCS again and works fine!
Don't know what happened but when I connect the Vac everything goes wrong! 😕
And, the problem is not on the circuit..... it can't be.
As I said I'm using two variacs in parallel. That are connected at the secondary of an isolation transformer. One variac is used for the Vdc of the CCS via a bridge and an electrolytic cap. The other is used for the Vac....
The first time the problem was that they were out of phase. Now I don't know what's going on....
But when I connected only one of the leads from the variac at the cap that is in series at the Vac I saw that the Vdc increased from 50V to 70V or more (don't remember exactly). When I connected the other lead the bridge got fried 😀
I think I must use a separate transformer to replace one of the variacs so the two sources will be isolated......
Don't know what happened but when I connect the Vac everything goes wrong! 😕
And, the problem is not on the circuit..... it can't be.
As I said I'm using two variacs in parallel. That are connected at the secondary of an isolation transformer. One variac is used for the Vdc of the CCS via a bridge and an electrolytic cap. The other is used for the Vac....
The first time the problem was that they were out of phase. Now I don't know what's going on....
But when I connected only one of the leads from the variac at the cap that is in series at the Vac I saw that the Vdc increased from 50V to 70V or more (don't remember exactly). When I connected the other lead the bridge got fried 😀
I think I must use a separate transformer to replace one of the variacs so the two sources will be isolated......
Hi resident,
You should run each variac through it's own isolation transformer, or power up a pair of transformers that will step the voltage down. Either way it will isolate you from becoming part of the power grid. The earlier failure was a warning to you.
Sorry for the delay. I just realized you were using only variacs with no isolation from the mains. This will also decouple the common connection and prevent another failure.
-Chris
You should run each variac through it's own isolation transformer, or power up a pair of transformers that will step the voltage down. Either way it will isolate you from becoming part of the power grid. The earlier failure was a warning to you.
Sorry for the delay. I just realized you were using only variacs with no isolation from the mains. This will also decouple the common connection and prevent another failure.
-Chris
What if I'll use one variac with the isolation transformer and the other directly from the mains? Or don't even think about it?
ok, I'll buy another isolation transformer or a step-down transformer....
I'd like to see this circuit works!
Do you have any idea how can we have more mA from this circuit? What if I'll use bigger transistors?
In the end I'll be happy if I can have a CCS that can deliver 500mA or more.... Any sources to read and learn about CCSs?
ok, I'll buy another isolation transformer or a step-down transformer....
I'd like to see this circuit works!
Do you have any idea how can we have more mA from this circuit? What if I'll use bigger transistors?
In the end I'll be happy if I can have a CCS that can deliver 500mA or more.... Any sources to read and learn about CCSs?
- Status
- Not open for further replies.