Mr carlson's curved tracer.

I just ordered a .47uF @ 1000V from mouser. It’s a lot smaller than the original.

@acockburn I just ordered some .47uf from mouser, thank you.

Now I am looking for the IC’s

Right now I am looking for one of these.
XR1468CN
MC1468L
SG1468N

Wonder if someone know where to buy that would be not a bad counterfeit. 

@larry_n7luf Yes, I came up short on those chips too. Rather than risk counterfeits I will just design a new PSU board similar to Pauls using a regulator I can source. One benefit of this is that if I design it myself I can have the board made fabricated by pcbway or someone similar. I’ll also make it SMD to save a little space although the transformer will by far be the biggest part.

@acockburn We I just to a chance and just ordered from china.

I have been taking screenshots of MCL video to enlarge to see where he place things.
Would have been nice watching him move each item.

He moved the power cord to an upper terminal strip, but not sure what else he may have move off the lower strip.

I do like how he has put two of the caps off the pin of the two power tubes and where he put that large resistor. ( I do have a Flir camera )

@acockburn I love it whenever I get a new part, it is like Christmas.

@larry_n7luf Wow… quite a nice looking transformer you’ve got yourself there Larry. With those solderable legs looks like a “King Size ” IC. I like it a lot. 😉

@larry_n7luf very impressive 🙂 I still have to make the curve tracer board before I even think about the power supply and I have a couple of busy weeks coming up so it will be a while before I get to that point – keep us up to date with your progress!

@acockburn I kinda got the cart before the horse.

I was busy buying the parts before I started to build.

I need to get back in my lab and back soldering some SMD, but have so many other things going on with my doctors right and spring time outside stuff.

@acockburn I’ve built a dual supply myself around the parts I (already) had at hand, based on the combination LM317 + LM337 Linear regulators and it works well.

The LM317’s can be set (via 2 external resistors) to output any voltage value in the range of 1.25 – 37V. The minimum overhead voltage needed for the regulation to keep going is 3VDC at a typical (Datasheet) and a minimum Current Load of about 3.5-10mA. The original MCL’s design (as far as I can tell) was designed to deliver around 50mA @17.5V.

Now, going back to the LM317 (discussion) the 2 external resistor (R1 and R2) values can be fixed value resistors and the calculation formula (to get the desired V out) is : V out = 1.25 x (1 + R2/R1) For R1 a value of 240 Ohms is “recommended” but, it can also be in a range of 100 – 1000 Ohms.

So the calculated values a came up with were originally R1=240 and R2=3.1K for a theoretical output of 17.5VDC

But then I thought to myself (Let’s make it, so it can be finely tuned via 2 additional VRs) so, what I ended up with for R2= is 3K (fixed value) + 250 Ohms (VR in series). This way I’ve managed to have a range of about 16.7 – 18.2V with the desired 17.5V being roughly “the center value” of the 250 Ohms VR. 

NOTE: knowing that the accuracy of the resistors is fairly tied I’ve used 1% resistors for the Fixed value and as for the VR I’ve had a bunch of them at hand and simply hand picked them by getting the ones that were the closest to 250 Ohms.

@ovi4 Thanks! I was thinking of something very similar and you saved me a lot of effort 🙂

Quick question – what is the function of the diodes strapped across the regulators? Is it reverse voltage protection, and is the one on the negative side the wrong way round or more likely did I misunderstand 😉

@acockburn Protection diode D1 is recommended when the smoothing cap C3 is used. The diode provides a low-impedance discharge path to
prevent the cap from discharging into the output of the regulator. And yes, well spotted that diode is indeed the wrong way around since I recreated the diagram in a hurry just to have it posted and didn’t noticed that. And by the way , when I fiddled with the above circuit I was even thinking of adding a tracking circuit to it so with only 1 VR you would actually be able to fine tune both rails at the same time and they would stay in sync with each other (voltage ways) and I actually archived that (with a 741 OP amp and some other resistors and a couple more regulators etc.) but I soon gave up on the idea realizing that the component count would increase quite a bit and so would the complexity. So for such an application when you simply need 17.5V (or there about) dual regulated PSU you won’t really need such tings added.

On another note: I don’t know if you’ve noticed but MCL used the regulation (part of the PSU) as a “voltage doubler configuration” since the voltage output on that transformer is only 2x 10V with a center tap (at the expense of having the current output halved) because it suited best for the application because that’s the transformer he already had at hand (as stated) but in my case I didn’t need to do it since I.ve already had at hand a suitable transformer

@ovi4 Thanks for confirming that about the diode, and thanks for putting the diagram together for me, really do appreciate it. I hadn’t clocked that Mr C’s was a voltage doubler, I’ll go back and take a more detailed look, out of interest but as you say it’s just what we have on hand, in this case I’ll buy according to what I need so this will work fine, I’ll try and find a transformer that fits nicely on a board and I’ll put a PCB design together for it when I get a chance, and share it back here for future readers of this thread.

@acockburn Well, there are many types/configurations of rectifications you can play with to adapt a transformer to a particular requirement and using the 2 diodes as e rectifiers and the 2 cap to basically get a positive rail and a negative rail (with the GND in between) is basically getting double the amount of the rectified voltage. Below is an updated version of the diagram for the transformer with 2x10V windings and a voltage doubler rectifier config.

@ovi4 Ah yes, that makes sense now I’ve had time to sit down and noodle through it – thanks again!

@acockburn there is even a fancier power supply of the same kind that I’ve stumbled across unintentionally. I was searching something else and spotted it. Apparently there are some additional filtering going and was purposely designed to have extremely low noise . best for audio preamps as well: