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I am currently a computer engineering student taking up basic electronics course. Right now we are learning how to etch a circuit on a PCB and our required output is to design a PCB layout for a working circuit using at least 20 components.

Currently, I am having a hard time looking for circuit designs that are easy to analyze and implement that meets the 20 components requirement. I'm looking for designs easy to analyze or understand since I am just quite a beginner in this type of area.

I'm not that knowledgeable on complex circuit designs, hence, I was hoping to look for circuits that are easy to analyze and implement. At the same time, circuits the can be easily implemented on a single sided PCB and can be auto-routed easily (since many components make it hard to manually route and auto routing usually end up with double sided designs which isn't optimal in most cases).

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  • \$\begingroup\$ Why? You have asked us to do something for you without explaining why. Is this for some sort of school work? If so, why can you not come up with a circuit yourself? Manually routing doesn't take long. 20 components isn't very many so an autorouter shouldn't be needed. Please give a little more context and details. You must at least have some idea of what you want your circuit to do \$\endgroup\$
    – MCG
    Jan 14, 2021 at 10:23
  • \$\begingroup\$ 20 resistors in series would do what you want but seems a complete waste of time. There must be more to the spec than a circuit with 20 parts? \$\endgroup\$
    – Colin
    Jan 14, 2021 at 10:30
  • \$\begingroup\$ Hi, I am currently a computer engineering student taking up basic electronics course. Right now we are learning how to etch a circuit on a PCB and our required output is to design a PCB layout for a working circuit. Currently, I am having a hard time looking for circuit designs that are easy to analyze and implement that meets the 20 components requirement. I'm looking for designs easy to analyze or understand since I am just quite a beginner in this type of area. \$\endgroup\$
    – Guorishix
    Jan 14, 2021 at 10:31
  • \$\begingroup\$ Others: As it was the question was puzzling and merited closing. The OP added details in a comment which made good sense of the request. I have added these to the question and reopened it. \$\endgroup\$
    – Russell McMahon
    Jan 14, 2021 at 11:42
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    \$\begingroup\$ How about a 8 bit binary counter with a 74hc and an octal buffer for driving 8 leds, each with their own series resistor. Add a button with a RC filter for debouncing, then some 100nF decoupling caps on the supply bins. \$\endgroup\$
    – Lundin
    Jan 14, 2021 at 11:50

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If you web-search 'simple circuit' and look at images you will find a wide range of potential examples.

Start with eg Simple circuits google search.

Ideas
Ideas here but less useful "everyday".


Bonus - I decided to try to locate the origin of the circuit below.
I found that sadly the originator, Tony van Roon died in 2011, but he has left a marvellous legacy of simple and often useful circuit. These are older circuits - well back into last century in some cases, and suitability for purpose needs to be checked in each case (but at a glance most seem bearably OK). As idea starters for modernisation they are excellent.

This web search turns up many of Tony's circuits.

Indexed list of Tony's circuits


Here is one-only which seems to meet your criteria - and it has the added bonus of being potentially useful.

This is a lead acid battery charger connected to an emergency light which is turned on when the input power source fails / is removed. The charger is everything to the left of the battery. The circuit has 20 components (excluding the battery) and all components are relatively common and/or could be easily substituted with similar ones.
The left to right functionality flow will tend to help keep the layout simple.

enter image description here

18 VDC (NOT AC as it says) power in at left. LM317 provides regulated voltage with Vbat set by R3 R2 P1 and adjusted by P1.
Q1 R1 R4 sets maximum current.
Ra turns light OFF when Vin is present.
When Vin removed Rb turns BC557 on which turns 2N3055 on which lights lamp.

Lamp could be a suitable LED(s) + resistor.
Transistors at right could be FETs . Q1 must be bipolar.

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Het sink for the circuit shown above.

This is only an example circuit BUT this shows what the PCB designer needs to allow for.

It has been suggested that adding a heatsink for the TO220 packaged regulator may be difficult for a beginner. A heatsink can be a simple L or U shaped piece of eg Aluminium with the TO220 package mounted flat and fixed with a single 3mm screw to the PCB. Or the heatsink and TO220 package can be mounted vertical. The small tabs seen on the 12 C/W heatsink below may be placed in holes in the PCB - or may be removed with a degree of loss of mechanical stability.

At say 1A load current the LM317 would dissipate 1 Watt per volt drop and the temperature rise for the 12C/W heatsink would be about 12 degrees C per volt of drop. For say 60 degrees C delta a 5 Volt drop would be allowed. So about 16 V in max DC with the battery at 11V.

The shown 18V in is unnecessary and also would need a larger but not large heatsink.

enter image description here

For much more on this site on TO220 and other heatsink design see here

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  • \$\begingroup\$ Thank you very much for this information. Sometimes I thought just randomly looking for circuits online is kinda misleading since some just "gets the job done" rather than really provide usefulness in the long term. That's why I sought for recommendations here knowing the chance I would be able to interact with those who really understand the area of interest. \$\endgroup\$
    – Guorishix
    Jan 15, 2021 at 13:47
  • \$\begingroup\$ LM317 in this case probably means a TO220 with heatsink and the whole ballet. Hard to get proper cooling done right, not ideal for beginner hand soldering. \$\endgroup\$
    – Lundin
    Jan 15, 2021 at 13:51
  • \$\begingroup\$ @Lundin Note that the OP's aim is to design a PCB to meet course requirements - building it may well be not required, || I surprised that you suggest that a TO220 with heatsink would be an overly challenging proposition. This takes 3 pads and a mounting hole if horizontal or maybe two if heatsink is vertical. Heatsink may be rudimentary or semi-serious depending on wattage desired. For a through-hole PCB the LM317 would be one of the easier components to solder. Yes? \$\endgroup\$
    – Russell McMahon
    Jan 16, 2021 at 10:27
  • \$\begingroup\$ Attaching the heat sink itself to the PCB might be mechanically challenging. And it should ideally be connected to a large copper area etc. \$\endgroup\$
    – Lundin
    Jan 18, 2021 at 7:14
  • \$\begingroup\$ @Lundin There is much on this site on heatsink design - but see above addition re a simple TO220 heatsink that would be easily accommodated by a beginning PCB designer. An L of aluminium suffices in many cases. \$\endgroup\$
    – Russell McMahon
    Jan 18, 2021 at 10:19
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A 555 timer with a few blinking diodes or other shenanigans will easily make a circuit with 20 components, and lots of things there to analyze. There are literally thousands of YouTube video's, tutorials and resources to assist in your understanding of the circuit. Your school probably has all the required components as well.

Autoroute is a supplementary tool to route specific mundane connections, typically on boards with hundreds of components. You never autoroute an entire board.

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One circuit you could make is a discrete reimplementation of a TTL LSI function like a gate (or a couple of them). Two 2-input AND LSTTL gates will go over this 20 component requirement. It should work on the first try, but probably won’t be quite as fast as the chip would be, since I suggest not to use the fastest transistors you can buy without having an oscilloscope of suitable bandwidth (and probes to go with it) to see the oscillations. Making 5GHz f_T transistors oscillate in a “beginner” layout is not hard. Use “slow” transistors similar to 2N2222.

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