An arguably better replacement for the resistor in a CRC power supply - R21 PS module

Hi tombo56, just looking at this design now and I find that the three parts listed below are either obsolete or out of stock on more than 1 year delivery at all the usual suppliers. Do you have any alternatives for these 3 parts?

All other parts are in stock at either Mouser or Digikey at the moment.

Q3 = ZTX958
Q3 = ZTX658
Q5 = SUP70101EL

Regards,
Gary.
 
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Hi Gary,
ZTX parts can be replaced with BC546/BC556. SUP70101 is the main reason why is hard to build this regulator from the beginning. Some company is purchasing any single peace available anywhere in the world for the last two years. Mouser expects 48.000 pcs. about November 15th.

However, these will never reach stock. That unknown customer will purchase all in advance, 2–3 weeks before they arrive. Only way to get SUP70101 is to purchase them now, as a part on backorder, and you will receive them when they arrive.

I also recommend as a better part for negative regulator, SQP120N10-09_GE3, which is on stock at Mouser. It is better matched with SUP70101EL-GE3.
If you proceed and get required parts, we can address some other details latter.
 
Tombo is right, I ordered my parts more than a month ago following his advice.

If you don’t manage to get them this november you will have to wait until the end of july next year
 

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I was thinking of building a couple of these modules, but according to Mouser the next delivery of SUP70101EL-GE3 isn't scheduled until April 2025 (see image below)!
In light of this information, I don't think there's any chance of getting them this November.

As such, sadly, I don't think it's feasible to go ahead with this project, it will have to remain on hold waiting for a more propitious moment! Or, until Tombo revises this project with available components! ;)

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With those wildly changing delivery dates, who knows what will happen. There is a mysterious large customer buying all these parts, so they might get in first. Good luck with ordering them.

It is worth noting that Digikey is showing April 2026 for its delivery of this part!

Surely there must be an alternative to use.
 
In my search for SUP70101 I reached out to a company based in Hong Kong that say they have stock - they are quoting almost $7 each which I wouldn’t mind paying for the small quantity that I need but can I trust that they won’t be fake? I’ve got some on back order with Mouser but no idea when they might come.
 
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Hong-Kong based distributors show stock of many hard to get parts. But when you actually make an order, in best case you’ll get reply that that they don’t have any. In a less fortunate turn of events, you’ll have to wrest your money back after receiving fake parts.