Just came in today and only took a few minutes to build. AC rectifier, LM317 & LM337 adjustable regulators, and filter/smoothing caps. No transformer but I am powering it with a 28-0-28 Triad VPL28-2000 transformer. Adjusts to well over +/-20VDC and with this XFMR has plenty of power. All of the resistors and caps were well within spec for a change. Not too bad for a $7 kit.


The smoothing caps that came are 2200uF Nichicons with 0 ESR.

 

For an even cheaper/simpler solution see this link – although both rails are limited to 100mA

https://forum.allaboutcircuits.com/threads/supply-rail-modules.174228/

 

There are also these single adjustable PSUs w/ XFMR for ~$13 but they also have very limited ampacity. Not a bad price considering that include the XFMR. No specs but with any kind of load they start dropping in voltage. They will only get you to ~15.5V. You need to add an inline fuse for protection.
Continuously Adjustable Regulated Voltage Power Supply DIY Kit +Transformer | eBay

 

Hi SamR. Do you have a link to the dual kit? The regulator heatsink pads look like rubber sheets instead of mica...not sure how much heat will transfer with rubber.

 

Hello,

The rubber looking pad can be made of thermal conducting silicon.

Bertus

 

They are silicone pads (haven't seen mica in years) and can be replaced by messy thermal grease. Dang, I thought I put the link in there. Here it is. Took ~3 weeks from china to Georgia.
Lusya DIY Kits LM317t LM337t linear Regulated DC Power Supply Adjustable Filtering board 5 40V DC F7 007|Amplifier| - AliExpress

Note it says 5-40V but that depends on the transformer you put in front of it.

 

not sure how much heat will transfer with rubber

They're likely thermally conductive. I've been using them since the late 70's.

 

Good to know, thanks.