EDIT: Thanks to @Sensacell for spotting an error. The current requirements for the LED have been revised. Just to be clear, there isn’t intended to be anything tricky about these circuits, they are intentionally pedestrian but just complicated enough to allow for various solutions that use very different approaches. Don’t fear and gotchas or hidden problems, and if like @Sensacell you spot any, please let me know!
Here’s a challenge intended to tease out some information about the state of design philosophy among the peers here on AAC.
This challenge is open to anyone, no matter your level of knowledge or experience. In fact, it would be extremely helpful to hear from people who consider themselves neophytes or less experienced. Your understanding of the best choices in the cases below is, for purposes of this investigation, equally important to the most experienced and knowledgable among us.
The goal is to design circuits that meet the requirements of the three scenarios below. These solutions need only be in principle. Schematics, simulations, and other rigor are certainly welcome but they aren’t required to answer the questions. However, the answer should include part numbers for actives and values for any passives that are critical to operation where possible. If for any reason you can’t calculate those values, answer anyway so the rest of the information is available.
Each of the circuits starts with certain baseline parts, as required:
The rest of the components are part of the design. There are no unstated constraints. The baseline components are given, and can‘t be changed, and the stated goal for each circuit is the only requirement for this challenge except for the unfortunately vague requirement the circuit be practical.
The goal for these designs is to come up with a solution you would actually build given the conditions. So, somewhat baked in are the optimizations you would make so the circuit could be useful. This isn’t a perfect specification, more of a spirit I ask you to employ.
There are three circuits and each has three versions for a total of nine. There is no requirement to provide all nine circuits to participate but for reasons of the data I would appreciate if you could do either three versions of one circuit, or one version of all three, Here are the version parameters:
So, here are the circuits, each involves blinking an LED according to parameters given:
1. Simple Blinker
Design a circuit that blinks an LED with a current of ~10mA ±2mA at a fixed rate between 5Hz and 10Hz. It does not require adjustability just a stable output in the given range. This should be accomplished with the fewest parts in addition to the given cell and one LED, so it starts at a count of 2. What would you choose, and why?
2. Variable Blinker
Design a circuit that blinks an LED from 1Hz to 100Hz at ~10mA ±2mA using the suppled cell, LED, and potentiometer. The accuracy of the interval just has to be basic, the adjustment range should be the full rotation of the pot, so very close to 1Hz when it is fully left and 100Hz when fully right.
3. Alternating Blinker
Design a circuit that alternately blinks two LEDs between 2Hz and 4Hz with a current of ~10mA ±2mA using the supplied cell and two of the LEDs. Like the first circuit, it must be a fixed rate in the range, no adjustment required.
So, what are your solutions to these challenges? I look forward to all answers.
Here’s a challenge intended to tease out some information about the state of design philosophy among the peers here on AAC.
This challenge is open to anyone, no matter your level of knowledge or experience. In fact, it would be extremely helpful to hear from people who consider themselves neophytes or less experienced. Your understanding of the best choices in the cases below is, for purposes of this investigation, equally important to the most experienced and knowledgable among us.
The goal is to design circuits that meet the requirements of the three scenarios below. These solutions need only be in principle. Schematics, simulations, and other rigor are certainly welcome but they aren’t required to answer the questions. However, the answer should include part numbers for actives and values for any passives that are critical to operation where possible. If for any reason you can’t calculate those values, answer anyway so the rest of the information is available.
Each of the circuits starts with certain baseline parts, as required:
 A 200mAH CR2032 Lithium Cell for Power [datasheet]
 1 or 2 Blue LEDs for Output [datasheet]
 0 or 1 10kΩ Linear Taper Potentiometer for Input [datasheet]
The rest of the components are part of the design. There are no unstated constraints. The baseline components are given, and can‘t be changed, and the stated goal for each circuit is the only requirement for this challenge except for the unfortunately vague requirement the circuit be practical.
The goal for these designs is to come up with a solution you would actually build given the conditions. So, somewhat baked in are the optimizations you would make so the circuit could be useful. This isn’t a perfect specification, more of a spirit I ask you to employ.
There are three circuits and each has three versions for a total of nine. There is no requirement to provide all nine circuits to participate but for reasons of the data I would appreciate if you could do either three versions of one circuit, or one version of all three, Here are the version parameters:
 Lowest Part Count—the fewest parts aside from the required ones
 Lowest Cost—cheapest to build in round numbers, don’t worry about too much rigor here, good faith estimates are fine
 Longest Battery Life—this may or may not be the same thing as lowest power consumption, but that’s probably good enough.
So, here are the circuits, each involves blinking an LED according to parameters given:
1. Simple Blinker
Design a circuit that blinks an LED with a current of ~10mA ±2mA at a fixed rate between 5Hz and 10Hz. It does not require adjustability just a stable output in the given range. This should be accomplished with the fewest parts in addition to the given cell and one LED, so it starts at a count of 2. What would you choose, and why?
2. Variable Blinker
Design a circuit that blinks an LED from 1Hz to 100Hz at ~10mA ±2mA using the suppled cell, LED, and potentiometer. The accuracy of the interval just has to be basic, the adjustment range should be the full rotation of the pot, so very close to 1Hz when it is fully left and 100Hz when fully right.
3. Alternating Blinker
Design a circuit that alternately blinks two LEDs between 2Hz and 4Hz with a current of ~10mA ±2mA using the supplied cell and two of the LEDs. Like the first circuit, it must be a fixed rate in the range, no adjustment required.
So, what are your solutions to these challenges? I look forward to all answers.
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