I built the originals on perf board. The kind that are just holes spaced at 1/10 inch, and used solid wire to connect everything (and component leads). A PCB is easier of course, but ther is nothing stopping you from going point to point.
Aside from worn out sockets, my original perf board still works fine. It is now over 20 years old.
Aside from worn out sockets, my original perf board still works fine. It is now over 20 years old.
Hi Steven,
All due respect, but that is not an alternative at all, not even close. I have several curve tracers and each and every one is inadequate for this task. Do you know why?
Please read the thread at least partially. The main, critical point you failed to notice is that the two devices must be held at the same exact temperature. That is how they are (properly) used and also how they must be matched.
All due respect, but that is not an alternative at all, not even close. I have several curve tracers and each and every one is inadequate for this task. Do you know why?
Please read the thread at least partially. The main, critical point you failed to notice is that the two devices must be held at the same exact temperature. That is how they are (properly) used and also how they must be matched.
I've read most (all?) of the posts in this thread. I have some questions regarding the matching board implementations. From a post by @anatech, I understand the rig runs with recommended supply voltages of 9v-15v. From the schematic provided by @Phloodpants (thanks!), I believe implementation uses a dual supply? Is that correct? So if I choose to run at Vs=10V I'll require a 10V to -10V supply?
Is there a benefit to using a dual supply as opposed to a single supply? I do think the dual supply is a clever way of biasing the NPN and PNP types. Could this be implemented with a single supply without disadvantage? Thanks.
Is there a benefit to using a dual supply as opposed to a single supply? I do think the dual supply is a clever way of biasing the NPN and PNP types. Could this be implemented with a single supply without disadvantage? Thanks.
Hi anoob,
Yes, bipolar supplies. It's just easier that way. The current source for tail current is the opposite polarity anyway, so it is just really easy to do both polarities. Using a single supply becomes much more complicated as the bases need to be referenced to some stable voltage.
As for voltage, I tried to stay close to factory testing conditions, which is 10 VDC collector - emitter. I find 11 VDC pretty close, but things work over a range of voltages.
A bipolar supply is very easy to make, not much more than a single supply.
Yes, bipolar supplies. It's just easier that way. The current source for tail current is the opposite polarity anyway, so it is just really easy to do both polarities. Using a single supply becomes much more complicated as the bases need to be referenced to some stable voltage.
As for voltage, I tried to stay close to factory testing conditions, which is 10 VDC collector - emitter. I find 11 VDC pretty close, but things work over a range of voltages.
A bipolar supply is very easy to make, not much more than a single supply.
Thanks anatech. I have a bipolar power supply so not a problem. I just populated phloodpants pcb so I'll be trying it out soon. (Gotta change my member name. Looks horrible in print 🙂)
Hi anoob,
The important things are that the 3mm, normal red LEDs poke though the holes of the TO-126 transistors with foam underneath. That and use good quality jacks / terminal headers. Do not use ones from Ebay or Aliexpress or other inexpensive vendors. You need quality here! I made several experimenting with various parts. You cannot afford anything but the normal industrial quality or better. It does make a difference. The 100R0 and 10K0 resistors are 0.1% (not a typo) with low temperature coefficients. Suggest Dale here.
The important things are that the 3mm, normal red LEDs poke though the holes of the TO-126 transistors with foam underneath. That and use good quality jacks / terminal headers. Do not use ones from Ebay or Aliexpress or other inexpensive vendors. You need quality here! I made several experimenting with various parts. You cannot afford anything but the normal industrial quality or better. It does make a difference. The 100R0 and 10K0 resistors are 0.1% (not a typo) with low temperature coefficients. Suggest Dale here.
Hey anatech. I followed your advice regarding using quality parts. Pretty much copied the board that phloodpants posted. Picture of my populated board shows better than words. Thanks!
Hey, that looks good. A huge thanks to Chris for designing a good version of the board.
You know you could alternate the current setting resistors and straighten the leads. They would fit better and look better. I guess the lead spacing for resistors could have been a bit wider, but that won't hurt electrical performance. The current and dissipation is low there, so if 1/4 watt parts fit better you can use them. It would fit much better.
I like to have the components laid down on the PCB because you are manipulating it constantly. That would keep them from being moved and eventually breaking the leads or solder joints. Consider you will have and use this for over 20 years. I still have my original perf board matcher, the original, first one. I wore it out and I bet it is 30 years old now. It still works.
See the two TO-126 transistors for tail current? I spaced them up a little with foam underneath as I wanted to stabilize the temperature and allow the LED and transistor to track temperature better. I put a block of closed cell foam under the transistor, the LED pokes through that and the transistor body as you have them. This isn't critical, it should work fine the way you have it.
Good job! (I can see you used good sockets). Now go ahead and get some use out of it. It will work fine as you have it.
-Chris
You know you could alternate the current setting resistors and straighten the leads. They would fit better and look better. I guess the lead spacing for resistors could have been a bit wider, but that won't hurt electrical performance. The current and dissipation is low there, so if 1/4 watt parts fit better you can use them. It would fit much better.
I like to have the components laid down on the PCB because you are manipulating it constantly. That would keep them from being moved and eventually breaking the leads or solder joints. Consider you will have and use this for over 20 years. I still have my original perf board matcher, the original, first one. I wore it out and I bet it is 30 years old now. It still works.
See the two TO-126 transistors for tail current? I spaced them up a little with foam underneath as I wanted to stabilize the temperature and allow the LED and transistor to track temperature better. I put a block of closed cell foam under the transistor, the LED pokes through that and the transistor body as you have them. This isn't critical, it should work fine the way you have it.
Good job! (I can see you used good sockets). Now go ahead and get some use out of it. It will work fine as you have it.
-Chris
Thanks Chris for all your help and advice. Phloodpants too. Re. the upright resistors, I should have ordered 1/4 watt ones. I think I'll go ahead and order them and replace the big boys. Wow 30 years. I'm impressed and also envious. I wish I had started my electronics journey way back when. I'm retired now but it's never too late. -Steve
Steve,
It's never too late.
I learn new things each and every day, and I love helping people understand things. Also to have them learn from my mistakes. When I started my career, there was no internet. All knowledge was hard won, or mentored. I've been doing this professionally for >45 years. Started in the early 70's on my journey for learning ... actually the 60's really.
Most everything I built as a kid or teenager still works today. My first kit was a Heathkit IM-18 VTVM, it still works.
It's never too late.
I learn new things each and every day, and I love helping people understand things. Also to have them learn from my mistakes. When I started my career, there was no internet. All knowledge was hard won, or mentored. I've been doing this professionally for >45 years. Started in the early 70's on my journey for learning ... actually the 60's really.
Most everything I built as a kid or teenager still works today. My first kit was a Heathkit IM-18 VTVM, it still works.
Funny this thread jumped back to life this week. I have been working on another PCB for the circuit, so now might be a good time to share, even though it is not complete yet. I use the transistor matcher a lot, and I find the collector resistors are vital for good matching socket to socket, so I decided to go SMD on this layout and use tight tolerance cheap SMD's to get very accurate matches. It might be overkill but I match to better then 0.1% so socket to socket deviation has to be minimal.
I also have the sockets oriented so that the faces of the transistors will be in contact, as they will be used in circuit. I have put some switches on so it can be turned on and off easily and the sockets flipped to verify the match is accurate.
Overall the PCB is over the top, but I think it will provide some pretty tight matching with less fuss.
I also have the sockets oriented so that the faces of the transistors will be in contact, as they will be used in circuit. I have put some switches on so it can be turned on and off easily and the sockets flipped to verify the match is accurate.
Overall the PCB is over the top, but I think it will provide some pretty tight matching with less fuss.
Hi fireanimal,
I used leaded parts to reduce temperature change.
You can make the basic circuit more complicated, but it won't buy you much or anything. I distilled and experimented with things decades ago. I boiled it down to what actually works very well. You are of course more than welcome to make it more complicated. The Vregs would help if you had a very coarse filtered, not regulated supply I guess. Even then I don't think the results would differ. It only takes one cap per rail to keep it from oscillating, and that was a precaution only. Use a Poly-Aluminum for overkill.
Mine had sockets for a jig so I could match various smt parts. A pain to clip down. The parts do not need to be face to face, only in contact. Foam isolates them from the outside, and a cover blocks air currents.
That's all you need. My PCBs only measure 3" x 3.5",and I made it larger to more easily handle. I didn't have any made beyond what I use.
I used leaded parts to reduce temperature change.
You can make the basic circuit more complicated, but it won't buy you much or anything. I distilled and experimented with things decades ago. I boiled it down to what actually works very well. You are of course more than welcome to make it more complicated. The Vregs would help if you had a very coarse filtered, not regulated supply I guess. Even then I don't think the results would differ. It only takes one cap per rail to keep it from oscillating, and that was a precaution only. Use a Poly-Aluminum for overkill.
Mine had sockets for a jig so I could match various smt parts. A pain to clip down. The parts do not need to be face to face, only in contact. Foam isolates them from the outside, and a cover blocks air currents.
That's all you need. My PCBs only measure 3" x 3.5",and I made it larger to more easily handle. I didn't have any made beyond what I use.
Turned out really nice, socket to socket deviation is less then .001% and will make matching a lot quicker going forward. Thanks again for the great circuit!
Hey Fireanimal!
That's a great board! I like it a lot.
Do you have an extra PCB you can sell? I'd like to build one up. No, I am not kidding.
-Chris
That's a great board! I like it a lot.
Do you have an extra PCB you can sell? I'd like to build one up. No, I am not kidding.
-Chris
it's not clear to me how to calculate the jig offset and the real Vc. My measuments are done with the dvm probes in the same position and only the trannies position inverted I have those numbers -7,5mV and -4,7mV