Building a DC to DC step up transformer

Discussion in 'General Electronics Chat' started by horsebox, Jun 16, 2007.

  1. horsebox

    horsebox Thread Starter Active Member

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    I was wondering if I could build a DC to DC step up transformer by making two solenoids and hooking up a potentiometer to the first one to create a changing current which should make a fluctuating magnetic field and hopefully induce enough voltage in the second solenoid to light up a small LED.

    Is it possible?
  2. thingmaker3

    thingmaker3 Moderator Staff Member

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    If you create a changing current, it can't really be called "DC" anymore.;)

    Beyond that, I don't understand the description. Can you post a diagram?
  3. horsebox

    horsebox Thread Starter Active Member

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    [​IMG]
    I cant draw for beans but there it is
  4. thingmaker3

    thingmaker3 Moderator Staff Member

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  5. horsebox

    horsebox Thread Starter Active Member

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    This is the kind of thing i was talking about only having an LED instead of a compass and a potentiometer instead of a switch.

    [​IMG]

    I think I finally understand inductance. Would I be right in assuming inductors only really work in AC circuits since it requires a changing magnetic flux to induce current?
  6. cumesoftware

    cumesoftware Senior Member

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    Being that the case, you will only detect current flowing through the secondary in the instant you switch the primary on or off, since only alternating magnetic fields can induce current, and that is why only in those instants you can induce current (because it varies). However, you can use a relay to create an astable "multivibrator" (equivalent to a vibrator in old valve equipment). To do that use the normally on contact of the relay in series with the relay coil/transformer paralel association. This works because once the relay is magnetized, it atracts the switch causing a break in the circuit (is a normally on contact, remember!), thus interrupting the current flowing through the relay coil, demagnetizing it again. The whole process is a cycle of on-off pulses.
  7. Joe24

    Joe24 Active Member

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    Well the mutual inductance of Transformers can also be useful when there is DC present. For example, a transformer can be used for DC Isolation in application involving cascaded amplifiers. By using a transformer in between two amplifiers, it can be used to keep the DC voltage on the output of the first amplifier stage from affecting the DC bias of the next amplifier.
  8. recca02

    recca02 Senior Member

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    change in flux linkage is required for inductance.
    and flux linkage is proportional to current.
    hence current variation is required.it need not necessarily mean an ac. only change in magnitude of current wud do.

    actually the rate of change is important
  9. cumesoftware

    cumesoftware Senior Member

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    Well, you won't need to have AC current. Any DC signal will do. As someone said, coupling transformers were used in amplifiers. It is not uncommon to see one in an old tube amplifier, feeding a speaker.

    Actually, you may see vibrators being used in tube radios that used batteries. The vibrator would create a pulsating current to feed a step-up transformer, so we would have HT for the valves.
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