One design rule of this project (and #Discrete YASEP) is to keep the part cost as low as possible. This in turn influences the choice and function of the parts. For example, this explains why I chose a Flash chip instead of a microcontroller, a CPLD or a dedicated decoder. In turn, this opens new kinds of functionalities.
Note : all the following prices are for bulk purchase on eBay or aliexpress, prices will vary and I chose an opportunistic approach where the parts I find influence the design, and not the contrary. It's different from a "perennial" design where parts are bought from Mouser/Digikey/Farnell/Element14 where obsolete parts are not stocked but you can buy as many pieces as you need and not much more. Overstocking lots from brokers counters the cost savings of not buying more than you need. However I have no idea how many modules I'll build (maybe 50-100 for the #Discrete YASEP) so it's a rough estimation. PCB costs and soldering are not counted either...
- AT49VB162AT : Found a lot with a unit price of 0.5$/pc
- 4014 LED : 0.01$/pc, ×36 = > 0.36$
- 74HC04 : 0.064$/pc
- 74HC74 : 0.125$/pc
- LDO 3.2V : old stock, price forgotten, let's say 0.1$/pc
- Mode LEDs : not chosen yet but the 4 would cost < 0.1$
- 2× N-MOSFET : I got a reel of 2N7002, forgot the price, let's say 0.05$
- 2× P-MOSFET : TBD
- Trimmer: TBD (0.2$ ?)
- buttons: 0.04×4=0.16$
- 2×16 pins : 0.32$ ?
- 26 resistors : values TBD, old stock, less than 0.05$
- Capacitors : I have reels of 100nF in several footprints, virtually free
So if thousands of these modules were manufactured, the parts cost would be around 2$. I can probably even reduce it a tiny bit more by dropping the 2N7002, the 74HC74 could drive the low-side directly, since the current is within the working range... But PCB fabrication, soldering, prototyping, yield and many other factors increase the overall price !