# Cannot for the life of me understand how to make this circuit for this lab

#### rmacke

Joined Sep 23, 2022
3
I am illiterate when it comes to drawn circuits and am struggling recreating the one in the attached diagram on my breadboard for an Electrical Lab for school, any help is appreciated.

#### WBahn

Joined Mar 31, 2012
30,035
What help are you looking for?

What is tripping you up?

Do you know how the internal connections on your bread board are set up?

Do you know how to use jumper wires to connect one strip of holes on your breadboard to another strip of holes?

Do you know how to identify which physical component corresponds to which symbol in the schematic?

Do you know how to identify which pin is which on those components where it matters?

#### MrChips

Joined Oct 2, 2009
30,792
Looks like 2E04 assignment. What have you learned so far about circuit analysis?

#### WBahn

Joined Mar 31, 2012
30,035
Looks like 2E04 assignment. What have you learned so far about circuit analysis?
What's "2E04"? I've never seen that designation.

#### Jerry-Hat-Trick

Joined Aug 31, 2022
551
Start by numbering each connection like this:
I've chosen 1 for the ground (negative rail) and 6 for the posistive rail as it's tidier to keep them apart. The emitter of the transistor is also 1 (i.e. ground) so I chose 2 and 3 for the base and collector respectively as the three legs are adjacent. Every component is then connected to their respective numbered rails.

Personally, I hate solderless breadboards, it's hard to see what's going on and connections fall out etc. Neater to place your schematic on a piece of wood and hammer small panel pins half way in wherever there is a number. Then solder in the wires and components to the panel pin tops.

#### Audioguru again

Joined Oct 21, 2019
6,688
I could barely see the green-yellow transistor, so I converted the schematic to black and white with increased contrast. I could not remove the grid of dots all over the schematic.

The moment that 12V is applied then the LED on the right side and probably also the transistor will burn out because nothing limits the charging current of the capacitor.

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#### rmacke

Joined Sep 23, 2022
3
What help are you looking for?

What is tripping you up?

Do you know how the internal connections on your bread board are set up?

Do you know how to use jumper wires to connect one strip of holes on your breadboard to another strip of holes?

Do you know how to identify which physical component corresponds to which symbol in the schematic?

Do you know how to identify which pin is which on those components where it matters?
I'm pretty much just struggling to replicate it on my breadboard, as I can't read circuit diagrams very well

#### rmacke

Joined Sep 23, 2022
3
Start by numbering each connection like this: View attachment 276825
I've chosen 1 for the ground (negative rail) and 6 for the posistive rail as it's tidier to keep them apart. The emitter of the transistor is also 1 (i.e. ground) so I chose 2 and 3 for the base and collector respectively as the three legs are adjacent. Every component is then connected to their respective numbered rails.

Personally, I hate solderless breadboards, it's hard to see what's going on and connections fall out etc. Neater to place your schematic on a piece of wood and hammer small panel pins half way in wherever there is a number. Then solder in the wires and components to the panel pin tops.
This is kind of helping me understand it better, but how would I go about my jumper chord placement using this schematic?

#### MrChips

Joined Oct 2, 2009
30,792
Look at some examples.

Begin by plugging in the 2N3904 transistor. Look up the pinouts for 2N3904 and follow the 1-2-3 pin identification.

Make sure all nodes #1 are connected to one supply rail.
Then connect all nodes #6 to another supply rail on the other side of the board.
Connect nodes given the same number.

Here is one example.

#### Jerry-Hat-Trick

Joined Aug 31, 2022
551
The moment that 12V is applied then the LED on the right side and probably also the transistor will burn out because nothing limits the charging current of the capacitor
I wonder if the LED and transistor would survive without thermal runaway if the capacitor charges fast enough! But the circuit as drawn must be wrong. I wonder if the intended circuit was something like:

#### Audioguru again

Joined Oct 21, 2019
6,688
I agree LED2 needs R4 in series with it to limit its current and the capacitor was in the wrong location.
I hope the wrong circuit was not designed by the "electronics" teacher.

#### Jerry-Hat-Trick

Joined Aug 31, 2022
551
I agree LED2 needs R4 in series with it to limit its current and the capacitor was in the wrong location.
Exactly. Moving the components around as suggested should make LED1 come on immediately the battery is connected, then LED2 should come on after a brief delay when the current through LED1 charges the capacitor up to 0.6V to turn the transistor on.

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