Electronics 2000

Hi, complete beginner here. I'm attempting a little project which needs the voltage reduced from around 5v to 7v down to a usable 3.6v. There is a diode in the schematic but I've no idea what type to use.

Thanks,
Lee.

Hi,

If you have a schematic any chance you can post it on here? Might well be a zener diode but without seeing the schematic it would be difficult to say for certain.

Simon (Webmaster) wrote:Hi,

If you have a schematic any chance you can post it on here? Might well be a zener diode but without seeing the schematic it would be difficult to say for certain.

Sure, it's a data transfer project involving wiring up a parallel printer port to a Playstation memory card reader but I need to drop the voltage down along the way:



Hope this helps.

Hi

Sorry for the slow reply. From the schematic the diode appears to be a standard rectifier or signal diode, not a zener diode (they have a slightly different symbol, assuming whoever drew the circuit used the correct symbol). If this is the case you could use a 1N4001 or similar diode. However the voltage dropped by a standard rectifier or signal diode is about 0.6V - certainly not the 2V you seem to need to drop it.

Really you'd need to check with the designer, or find the parts list / notes that go with the diagram. If no diode type is specified I would think the intention is indeed to use a bog-standard rectifier or signal diode.

Many thanks Simon.

It's been suggested to me that I'll need to use at least two or three of these diodes in series to drop the voltage down, sounds about right. I'll check the voltage levels as I go to be safe.

In case anyone's interested, I found a page explaining how a PC parallel port can be utilised for similar projects:

http://www.epanorama.net/circuits/parallel_output.html

I misread your post yesterday as needing to drop to 5V - I see you actually need to drop to 3.6V. As suggested to you, you'll need a least 2 diodes for the minimum input voltage (5V), possibly 5 or 6 with a 7V input. As you say the best thing is to measure as you go, or to use a different method of dropping the voltage, such as a zener diode and resistor.

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