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S-24-x 12V 2A or 24V 1A low cost power supply

I recently came across this relatively cheap power supply for my projects. It features a single chip switch mode IC which has an integrated high voltage NPN transistor for the switching.

The design was curious because of the lack of filtering etc.

The Design

The power supply is built around the IC DK124. Essentially its quite a convenient package which requires a minimal number of support components.

The pinout of the IC is shown below.

The datasheet also shows you an application circuit with values and also how to calculate the transformer for your application.

Youtube’s bigclivedotcom has a nice video analysing/explaining the operation of the circuit so I won’t bore you with the details. However his version was a clone according to his comment(s).

The datasheet for this IC can be found here:
http://grupoautcomp.com.br/wp-content/uploads/2016/11/Specification-IC-DK124.pdf

If its not available you can download a summary here: Condensed-DK124.pdf

The Problem

Unfortunately the seller accidentally sent me a mix of 24V and 12V versions when I specifically ordered all 12V@2A versions.

Add to that the impending Chinese New Year Hiatus, I was left to figure out how to turn the 24V into a 12V.

Turns out 90% of the components inside are identical except for the feedback circuit…

I discovered that resistors R5, R6 and VR1 are the only differences between the two boards.

Below is a table of the values:

Part12V version24V version
R520K75K
R64K78K2
VR12K200R

The quickest conversion is to replace those parts verbatim. However i decided I would try to retain the pot and attempt to change the voltage divider to suit.

The feedback circuit

First I set the 12V version to output a stable 12.10V. At that point I measured the 2K potentiometer to see what value it read. It read 562R.

The simplified feedback circuit is as follows:

With VR1 set to 562R, the equivalent series resistance with R6 is 4700R+562R = 5262R or approx 5K3. The voltage at the TL431 ref pin would be 2.5V as expected.

So to retain the pot on the 24V version, I just need to figure out the voltage divider values that will bring the same 2.5V vref.

After some experimenting around I figured out to retain the 200R pot, I can use the following R5 and R6 values.

R5 = 18K and R6  = 4.7K while VR1 remains at 200R.

This will give a nice adjustable range of 10.5V to 12.1V

Purchase

If you are considering buying this power supply. May I offer my affiliate link which while it helps me out, costs you nothing extra. In fact I can vet the quality of the unit as shown in the photos.

http://ali.pub/27ybgf

 

 

 

 

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Baofeng UV-5R with 3800mAh battery

Low cost Ham Radios

With the advent of best practice design and the reduction of cost-per-unit via high volume manufacturing, it was only a matter of time before we would see a “good enough” radio enter the price range of persons wanting to enter the HAM Radio scene.

Me personally, I wanted a radio to ensure my safety in times of social chaos during natural disasters where coordination is of the utmost importance to preserving life. Notably, during times like these, the grid infrastructure is unable to cope with the added volume of communication requirement. Hence, its likely your cellphone will stop working or have limited use. To qualify this Im not a prepper but I do see their point of view as being valid to some extent.

And no, Im not going to store cans of food in my basement.

Baofeng UV-5R

It would appear that there are a plethora of reviews out there on this particular radio from the HAM snobs to the newly initiated and budget conscious persons. So Im not going to go into any deep review of the base device except to review the larger battery.

Battery Life

The base model UV-5R comes with an 1800mAh battery. This “upgrade” model comes with a 3600mAh battery. Although you can buy an upgrade battery for your existing radio, since I was entering the market for one/two I decided I would find a source that sells the 3600mAh battery as part of the base product.

Well I can say the larger battery feels secure and for someone with larger hands this makes the UV5R easier to handle and work with. The added standby and talk life is an added benefit.

The battery, even though its an aftermarket addon, doesnt feel loose or unstable like some other radios. It feels like it was meant for it.

I would highly recommend you get the 3800mAh version if you are new to this radio and considering purchasing one.

My Purchase

Although there is no official Baofeng store on Aliexpress (just supposedly licensed stores), I picked a store that had a really good price and good feedback.

This is my affiliate link. It helps me out without any extra cost to you and the added benefit of a verified seller.

http://ali.pub/2anv93

Note that this seller has sales from time to time. This is a snapshot of what I paid:

That’s pretty decent for 2 units delivered in a timely manner.

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DIY Keg Cleaning System

Last Call

If you use a dispensing keg by racking your cold crashed but unfiltered beer, you will end up with some trub at the bottom of the keg which when it comes time to  clean is a fairly simple task IF you have small enough hands and forearms.

Over the last 2 years I’ve been experimenting with dry hopping in the dispensing kegs amongst other additions and these additions can result in some stubborn stains/residues in the keg.

It can take a considerable amount of water sprayed in at high pressure to dislodge residues, a resource and time consuming process.

Cleaning In Place

Cleaning in Place (CIP) has been around for approximately 50 years, and is commonly used in hygiene critical industries, such Food, Beverage and Pharmaceutical, to clean a wide range of plant. CIP refers to the use of a mix of chemicals, heat and water to clean machinery, vessels or pipe work without dismantling plant. The process can be one shot, where everything goes to drain, or recovery, which recycles most of the liquid. Overall, CIP can be a very efficient way of cleaning.

I decided I would work with a recovery system which I can then pump out to drain.

The Design

I figured the setup would be connected to my Brewery’s wash area (large sinks and sprayer taps). Effectively I would need:

  • a CIP spray device that fits inside the keg
  • a pump that can create enough pressure to operate the CIP to an acceptable level
  • a way of timing the clean
  • a way of draining out the waste liquid
  • minimal connections / established connection methods to minimise complexity and cost

The Parts Required

Below are the parts you will need to build one keg cleaning system. You can easily adapt my design to more than one keg by adding more lines.

THE CIP spray device

I found this nice CIP rotating ball with a DN15 female (1/2BSP) thread.

This is CIP head I used. A really good price too.

http://ali.pub/2974r1

THE PUMP

Mains water pressure here is around 120-130psi. The pump below is economical, runs off 12V and has DN15 male fittings (standard water fittings in Australia).

Specifications:

  • 12VDC @ 7A (Approximately 80W)
  • 5.5Litres/min flow rate
  • 0.9Mpa / 130.5psi / 9 bar maximum pressure

I got the pump from here. It was the cheapest price I could find. The store had a 48% off sale (so wait for that).

http://ali.pub/2974m6

IMPORTANT: Make sure you ask for the DN15 version (Type D) of inlet and outlet. OR you can replace the braided hoses with clear PVC tubing to suit the M18x1.5 stock thread with barb.

If you want to use the M18x1.5 version, you will need these adapters:

http://ali.pub/2b6269

Then you can use the normal garden style disconnects:

12V 10A Power supply

I used a power supply designed for LEDs slightly overrated to the requirement to ensure longevity.

I got my adapter here. It comes in various plug configurations. Make sure you pick the right one for your region and to suit the pump’s DC input.

http://ali.pub/2974zl

The Keg Lid

In my design, you take off your existing keg lid and fit this keg lid which has the CIP cleaning head attached to it. The Lid is optional if you wish to keep the costs down but this way you can run the keg in any direction for cleaning.

 

 

The lid will need to be modified to adapter the CIP head to a bulkhead connector to attach to the output of the pump.

Options:

Used Keg Lid. If you want to save some money get this used keg lid which you will modify anyway.

http://ali.pub/29759i

Brand new keg lid.

http://ali.pub/2975ao

Various Bits

You will need the following bits to complete this setup.

Cornelius Keg liquid disconnect

Barbed version is acceptable here as  you will be connecting hose directly to it. I use these disconnects and they are a damn sight better than the cheap rubbish out there and also cheaper than the original Cornelius ones http://ali.pub/2975zd

Stainless steel DN15 male to union

This is to connect the CIP head to the pump’s output line. http://ali.pub/297666

UPDATE: I have changed this to a nylon version which has orings. I find this will seal the union better than stainless steel. However note, if you are running high temperatures stick to stainless steel!

http://ali.pub/297bc9

Stainless steel DN15 to 8mm barb

This is to adapt the cornelius disconnect barb to the DN15 hose to the inlet of the pump.

http://ali.pub/2976go

DN15 Stainless steel braided water hoses

I recommend you use mains water pressure rated hoses for this job as you are dealing with high pressure and possibly temperature. This was a bargain. You get four hoses for the price… http://ali.pub/2976bm

Choose your lengths to suit your setup. I used 60cm versions. You will need two of them (Pump inlet and outlet).

Mains Timer Switch (up to 60mins)

I used this timer switch to let the cleaning go for the time I need it to go for without manual intervention required.

Specs:

  • Plug Type: AU Plug but choose the one you need for your setup
  • Voltage: AC 220V/50Hz (Again, choose what you need)
  • Max power: 2200W (plenty for this setup)
  • Setting Time: 2-60 Minutes (plenty for washing a keg)

http://ali.pub/2978bd

Sundries

You will also need a short length of 6mm ID 8mm OD beer dispense hose (hard clear stuff NOT the soft PVC/silicone). The length is up to you but I recommend you keep it short as its not that flexible. I kept the length to 100mm; enough to adapt the disconnect to the 8mm barb to male DN15 adapter.

You may require some plumber’s teflon tape to connect the DN15 male union to the CIP head.

You will also require a step drill to 19mm/20mm to drill out the keg lid.

Putting it together

 

  1. Drilling out the lid. You may choose to retain the safety relief valve and drill a completely separate hole but in this setup you do not need it so I drilled out the safety valve recess to 19mm/20mm so that the DN15 union fits through snugly. NOTE. You do not want this loose.
  2. Use thread sealer and fit on the CIP head to the keg lid.
  3. Keg Lid modification Done. NOTE: It can be a little bit tricky to get this to fit into your keg but once you figure out the motion it will easy to remove/fit.
  4. Connect one of the DN15 hoses to the other side of the DN15 union on the keg lid.
  5. Connect the other end of this hose to the pump’s output side.
  6. Fit the beer hose to the disconnect. Note that no hose clamp is required.
  7. Fit the other end of the hose to the barb end of the DN15/Barb adapter.
  8. Connect the remaining stainless steel hose to the DN15 barb.
  9. Connect the other end of this hose to the pump’s inlet.
  10. Youre done!

You should have a setup as shown below in the diagram.

I hope you will enjoy putting this cleaning system together for your setup!

Updated Design 2018

I ended with the M18 version of the pump. Here is my new configuration:

Parts required

DN15 (1/2″) MALE to DN20 (3/4″) FEMALE Adapter http://ali.pub/2cuval

DN20 (3/4″) FEMALE to 16mm quick connect MALE http://ali.pub/2ew6yp

16mm quick connect FEMALE to 1/4 barb http://ali.pub/2cuvum

16mm quick connect FEMALE to 13mm (1/2″ ID) hose http://ali.pub/2cuvxx

OPTIONAL: Adapter for QC. If you want to extend pipes. http://ali.pub/2cuw18