Low voltage-drop diode needed

[WhenBoredomPeaks]

I guess i need a low voltage drop diode in my ADA Flanger clone.



I soldered 1N5819s on the PCB instead of 1N5817s because that was the only diode i could find. (these are around the LT1054 charge pump IC) A few days later i checked the datasheet and i found that the 1N5819s will have at least 1V voltage drop each so i will have something like 16V going into my 15V regulator which is not enough.

Now i can find the 1N5819 everywhere but i no one seems to carry the 1N5817.

What kind of other low-voltage drop diode i could use there? (I guess low voltage drop is the key because we are pretty close to the minimum voltage requirement of the 15V voltage regulator)

[midwayfair]

The 5819s I have at home have a lower Fv drop than 5817 -- closer to .18v on them instead of .2v on the 5817.

Datasheets can be very confusing about the forward voltage of diodes.

Tayda sells the 5817, that's where I tend to get mine.

If your're using a battery, make sure it's fresh. If you have a series polarity protection diode at the 9v input, you may need to remove it.

[WhenBoredomPeaks]

The 5819s I have at home have a lower Fv drop than 5817 -- closer to .18v on them instead of .2v on the 5817.

Datasheets can be very confusing about the forward voltage of diodes.

Tayda sells the 5817, that's where I tend to get mine.

If your're using a battery, make sure it's fresh. If you have a series polarity protection diode at the 9v input, you may need to remove it.

Im in Central-Europe, so ordering 2 diodes from Tayda is out of the question for me.
On the other hand if your diodes will be similar to mine then they will be fine in this circuit.
There is a 1N4001 protection diode on the input of the regulator. (i hate batteries btw, i haven't bought a battery since 2008)

[midwayfair]

There is a 1N4001 protection diode on the input of the regulator. (i hate batteries btw, i haven't bought a battery since 2008)

Just to clarify: Is it in series with the power supply, or is it reverse-biased to ground (that is, the anode is connected to ground, and the cathode to +9v?

A 1n4001 in series with the input would drop your power supply to about 8.5. Drop that another half a volt from the Schottky diodes, and you end up with 8v -- doubled is 16. If it's a series diode, you can replace it with another 1n5819 and you'll get something closer to 16.5 v, or just omit it and you'll get 17v or more.

[R.G.]

Now i can find the 1N5819 everywhere but i no one seems to carry the 1N5817.

The 5819 is the higher-reverse-voltage version of the 5817. They are both 1A Shottky diodes, and have about the lowest forward drop of any silicon diodes.

Germanium diodes are actually lower than silicon Schottky diodes. I don't know how much current you're putting through them, but if you have some otherwise trash, low gain germanium transistors, you can hook them up with the base shorted to emitter and use the collector-base junction for low-drop diodes at modest currents, under maybe 100ma.

[analogguru]

Im in Central-Europe, so ordering 2 diodes from Tayda is out of the question for me.

Have you ever heard of evilbay ?

http://www.ebay.de/itm/20x-Schottky-Diode-1N5817-/121068812118

20 pcs for € 1,-- BIN - I think you won´t get them cheaper.

analogguru

[roseblood11]

http://uk-electronic.de/onlineshop/product_info.php?products_id=229&language=en&osCsid=4d79843d6642c36232c8cef8ee82ed64