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Topic: Power Supply (Read 5803 times) previous topic - next topic

retronet_RIMBA1ZO

WOW, look at those solid looking toggle switches !!
nothing like the dinky plastic ones we get nowadays !

Jiggy-Ninja



Hmmm... I'm just saying what was there... I know these things were cheap... but there were 4 1N4001's in a bridge configuration... I agree that a lot of these things would just use 1 diode with a filter cap.

how would that circuit look like ?
isn't using 4 diodes a "minimum" requirement for the rectifier in a power supply (AC to DC) ?
http://electronicsclub.info/diodes.htm#bridge


4 diodes is the minimum for a full wave rectifier. If you're satified with half wave, you can use only one diode in series with the load.
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retronet_RIMBA1ZO


4 diodes is the minimum for a full wave rectifier. If you're satified with half wave, you can use only one diode in series with the load.

i see - okay, and that means half the voltage, right ? (compared to if one used the full wave rectifier?)

CSGuy


WOW, look at those solid looking toggle switches !!
nothing like the dinky plastic ones we get nowadays !


They are all metal. Probably why this thing still plays games after 44 years-good components. I use it almost every day.

It has one huge capacitor in it, but that can be replaced very easily if that goes bad.

I just make sure to unplug it every time I'm done playing it. I never leave it plugged in while it's not being played. I have no idea what that would do, leaving a 44 year old electronic plugged in 24/7.

polymorph

The TO220 case part in the  bottom left corner is an LM7805 linear 5V regulator. The large grey cylinder above it will be a Vcc bypass/smoothing capacitor, and the green thing between them is also probably a Vcc bypass capacitor.
Steve Greenfield AE7HD
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CSGuy


The TO220 case part in the  bottom left corner is an LM7805 linear 5V regulator. The large grey cylinder above it will be a Vcc bypass/smoothing capacitor, and the green thing between them is also probably a Vcc bypass capacitor.


I'm glad you can see all that from that tiny picture.  :smiley-eek:

polymorph

Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

Grumpy_Mike


i see - okay, and that means half the voltage, right ? (compared to if one used the full wave rectifier?)

No the voltage is the same, it is the peak of the signal. However you only get these peaks half  as often with half wave rectification therefore you can not pull as much current from the supply before the voltage starts sagging.

retronet_RIMBA1ZO



i see - okay, and that means half the voltage, right ? (compared to if one used the full wave rectifier?)

No the voltage is the same, it is the peak of the signal. However you only get these peaks half  as often with half wave rectification therefore you can not pull as much current from the supply before the voltage starts sagging.

thanks, Mike !
i was "half"(!) resigned to seeing that question sink away (unanswered).

would an oscilloscope be necessary to "see that in action" ?
(the half wave, not the question sinking !! :D )

"you can not pull as much current" - shouldn't the rating on the equipment reflect the effective current if it's "only a single diode" rectifier circuit ?

polymorph

If a given power supply using a single diode is rated for, say 9V at 500mA, then yes, it'll put out 9V at 500mA. The current rating is a function of the resistance of the transformer wires and the size of the core.

But for a given transformer and smoothing capacitor, it can put out more current with a 4 diode bridge rectifier. Both because there is only 1/2 the time between charging peaks into the smoothing capacitor, and because the maximum current through the winding resistance is drawn 2x as often to charge the smoothing capacitor and therefore provide power.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

Grumpy_Mike

#25
Mar 06, 2014, 05:01 pm Last Edit: Mar 06, 2014, 05:10 pm by Grumpy_Mike Reason: 1
Quote

would an oscilloscope be necessary to "see that in action"

Yes although there are plenty of graphs on the net.
There is a lot here that you don't want to know but there is stuff you do as well
http://en.wikipedia.org/wiki/Rectifier

These pictures might help:-

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