Cadet/Castle components sources and substitutions


  1. You can substitute LT1256 for LT1251 in any of the Cadet designs
  2. At LZX we have sourced LT1256 in the past from Mouser and directly from Linear Technology/Analog Devices.


Hello everyone :slight_smile:
Is there a thread on here specifically for questions about the components required for the DIY cadet series? I typed “Cadet” into the search this seemed like the most relevant thread.
I’ve a couple of simple questions. My first, is there such a major difference between a 2n3904 and the 2N3904BU that I should definitely only use the BU version? (Same for the 2906).
Pretty much the same question for the TL431BQLPM and a TL431 or the TL431a, my local store stocks the last two but not the BQLPM variety.

I did quite a bit of reading through the datasheets of the ATMEGA88A-PU and the ATMEGA88 to see their exact difference, (I’d include a couple of screenshots I took but I can’t attach them here for some reason). The Atmel ATmega48A has an operating voltage range of 1.8V - 5.0V and the Atmel ATmega48 has an operating voltage range of 2.7V - 5.5V.

Thanks for any help, tips, suggestions and explanations, Robin in Berlin

PS. I’ll be on holiday for 3 days as of tomorrow.


Hi Robin!

We can use this thread for those questions, I’ll change the title. :slight_smile:

  1. 2N3904 and 2N3906 is OK. These are generic NPN/PNP parts.
  2. TL431 variants, check the datasheet to make sure the pinout is the same as the one specified. Some of the variations have different pinouts. If pinout matches it should be okay. LM4040 is another substitute. These are all 2.5V precision voltage reference parts.
  3. I believe the source code will need to be adjusted and recompiled if you wanted to use a part other than ATMEGA88A, so that’s not an option. Are you having trouble sourcing this one? We ship all PCB+Panel sets with a pre-programmed ATMEGA88A.



Here’s a few alternate toggle switches with shorter bat style levers. All of these will require hand wiring.





Mountain Switch 10TF230 for DIY modules? (VCO)

Hello and thanks for your informative reply @creatorlars :smiley:
Regarding the ATMEGA88A, I think the seller has missed placed it. It shouldn’t be a problem thankfully.
Talk soon, Robin


I did quite some reading but it was quite clear that the BQL version has a much higher temperature tolerance, as much as 125 degrees Celcius if I’m not mistaken. The regular version and the ACL I found could only stay steady till 70 degrees C. Do modules like the LZX cadet range generally operate at higher than 70 degrees?


No, they don’t run hotter than 70 degrees C. More like 40-50 C at the most. The higher temperature parts are rated for automotive or industrial use, but there’s no problem with using them.


Thanks Lars for the temperature explanation :slight_smile:
I guess it’s the power supplies where all the heat is generated and given off.


Not always – voltage regulators at the inputs of modules and some of the higher current ICs can sometimes generate heat as well. Nothing in the system ever gets hot enough to need high temperature rated ICs though. If you’re wondering why I picked the original partnumber I did, it’s probably because that part had good stock levels and a better price when I originally selected parts for the BOM. Even though there are many possible variants and alternate parts, I always prefer to list a very specific part to avoid confusion. Learning when and how to substitute is part of the learning experience I hope building these DIY modules will provide!


If anyone is looking for decent pricing on LT1256 ICs, check out Arrow Electronics. They have them for $7.33 and if you are a new customer, you’ll get 30% off your first order. Wait, it gets better. Free FedEx shipping!

So far I’ve placed two orders through them and shipping from The Netherlands to California was faster than from Mouser to Los Angeles.


crossposting from the switch thread since this one is a sticky…

The following E-Switch parts are drop in replacements for the Mountain Switches specified in the Cadet BOMs. Note that like the original SPDT, the below SPDT has right angle legs too short to reach the PCB holes and you’ll need to use some extra wires such as resistor leg cutoffs to splice them in.

These parts are also quite a bit cheaper than the originals or many substitutes.

SPDT, right angle, non-threaded bushing, short toggle, part no. 100SP1T2B4M6QE, $3.32/1 piece

DPDT, right angle, non-threaded bushing, short toggle, part no. 100DP1T2B4M6QE, $4.21/1 piece


as a tip: you can get free LT1256 / LT1251 samples from Linear Technologies.
I think the maximum is 2 of each. They also have other interesting IC’s, so get those too :slight_smile:


just tried to get the LT1251 sample from Linear Technologies - you need a business email (which I don’t have ) to get them!!!


I noticed that when I got a sample. I felt a little funny telling them that I needed two LT1251’s for my job at a book store, but they sent them anyway!


Don’t feel bad about taking them up on those free ICs. I used to get them and now we buy 1000-2000 at a time sometimes! Shapechanger alone has 8!