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## How do i breadboard this simple circuit??

Hello: Im self-studying electronics and am currently using the Heathkit DC,AC and semicinductor course books. Im finishing up "DC electronics" and getting ready to start the AC electronics course. However at the end of the DC course book there is a experiment ( number 21 ) on page 8-49 that shows how to use capacitors as a " voltage doubler". Im also using the heath analog trainer which is a breadboard with built-in variable ac and dc power suppiles. Pics of it are easily googled. the circuit consist of a 470 and a 47 ufd electrolytic capacitor, and a DPDT slide switch with wires soldered to the 3 post on one side of the switch. The circuit has 5VDC appiled to it. The 470ufd is "C1" and the 47ufd is "C2" . When the switch is slid up it is in "A" posistion and down it is in "B" posistion. The circuit is wired up so that in switch posistion "B" C1 is placed accross the power supply and charges to 5VDC. In posistion "A" cap C2 is now placed in series with C1 and power supply and shows 10 volts on the voltmeter via the 5VDC on C1 and 5VDC on C2 in series. There is a schematic diagram of the circuit showing one lead of C2 connected to the neg post and the other lead left floating until switched in sereies with C1. I simply cannot understand how to wire the switch in so that it switches C2 from parellel with the power supply to in series with C2 and the power supply. Im sure it is embrassingly simple. If anyone has acsess to the DC electronics course book maybe you could draw a pictorial diagram of the circuit on the breadboard and post it here?? Or perhaps try to explain on here how it might be breadboarded. This is what the books says about the circuit : " This experiment demonstrates the operation of a circuit called a voltage doubler. When S1 ( the switch) is in position B, C1 is connected directly across the power supply. Therefore C1 charges to 5 volts. Now, when S1 is switched to position A. the 5 volts across C1 is placed is series with the 5 volt power supply. Thus, the total voltage from the top of C1 to the GND terminal is 10 volts. with S1 in position A, C2 is placed across the series combination of C1 and the power supply. Consequently, C2 charges to almost 10 volts. The net effect is voltage is almost boubled. " Any help will be most wqelcome. Thanks, Joe B KC4LNX.

2. Ham Member
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S1 is a DPDT switch.

With a little thought and drawing all the elements with pencil in hand to create connections, you should be able to figure it out from there.

73

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I think the switches are symbolic of the diodes in a real voltage doubler power supply.
I've never heard of anyone making one using real switches,but I guess it can be done!

73,VK6ZGO

4. Ham Member
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Originally Posted by VK6ZGO
I think the switches are symbolic of the diodes in a real voltage doubler power supply.
I've never heard of anyone making one using real switches,but I guess it can be done!

73,VK6ZGO
It is not an example of a circuit that one might actually use in the real world, it is an example that illustrates the concept of capacitive voltage doubling for the student.

The Heath/Bell & Howell electronics courses were very good stuff indeed, back in the day. Anyone working with it today should benefit greatly from the experience. Sound basics presented in a very good order, this course enabled quite a few to go from zero to First Class Ticket (1st Class FCC License) when it was in its heyday.

Yes, the switches do indeed represent "manual" diodes at this stage of the learning experience.

73

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Thanks for all the replys. Im going to keep pondering on it .I can hook up the circuit so that C1 is in parellel with the power supply, or i can hook it up so that C1 and C2 or in series with the power supply, but i cant seem to wire it so that the DPDT switch will switch the caps from parrellel to series. Im sure i will figure it out.. Joe B

6. Picture the DPDT switch as TWO SPDT switches, that are In Sync with their operation.

What points in circuit are identical whether Capacitors are in Series or Parallel? Input and Output.
What Changes? The interconnections between the other end of those capacitors (A, B).

The CENTER POLE of a DT switch is normally wired to that COMMON point.
So, One Pole is for Input to One Capacitor (A); Other Pole is for Output from the Other Capacitor (B)

Now how do you wire that DPDT switch ..
So capacitors (A, B) are Series in One Switch direction and Parallel in the Other Switch direction??
Last edited by W9GB; 05-28-2012 at 08:16 PM.

7. BUT How do I wire this switch??

1.) Solder one lead of capacitor (A) to CENTER POLE of DPDT switch.
2.) Solder one lead of capacitor (B) to other CENTER POLE of DPDT switch.
3.) One free Leads goes to Input, the other to Output.
4.) At one end of the switch, Jumper the 2 Poles together -- this is the Series selection.
5.) For the other switch selection, you wire a jumper from the switch pole to its opposite ....
Input capacitor -- jumper goes to Output. output capacitor -- jumper goes to Input.
THAT gives you parallel capacitors.

Draw on a sheet a paper -- until you understand (spatial thinking).

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