NJM386B IC at 22volts?

[hugcd]

Browsing for IC's for a Ruby i came across this website that has a New Japan Radio NJM386BD with the following specs:

No of chanels: 1
Gain bandwidth -mom: 600KHz
Gain: 49db
Supply voltage max: 22v
Output power: 1000mW

http://www.futureelectronics.com/en/Technologies/Product.aspx?ProductID=NJM386BDNEWJAPANRADIO8037301&IM=0

On the NJM website they have a NJM386B (not BD) and its maximum voltage is 18v. I guess it might be a mistake but it would be great to have a 386 IC that accepts 22v that way it would be safer to run it at 18v.

[R.G.]

Yes. If you HAVE to use 18V for a supply, use the BD.

[hugcd]

Thanks! Good to know. Too bad is not in stock now. I looked at Octopart for a NJM386BD and doesn't seem to be anywhere else or if they have its listed at 15v or is not a through hole IC, that is weird.

[PRR]

LM380 is a very similar chip (actually grandpa to 386) and rated 22V.

http://www.ti.com/lit/ds/symlink/lm380.pdf

LM380N-8 is 8-DIP. If you load it with less than 16 ohms, at 18V-22V, it will cook.

LM380N is 14-pin. If you solder the 3 unused legs in the middle each side to a scrap of copper, it will handle 8 ohms at 18V and deliver 4 Watts audio output, which beats the piss out of any abused 386.

[hugcd]

Thanks PRR! I have been lately debating between the LM386 and the LM380 and everybody seems to point me towards the 380. Getting the 8 omhs at 18v out of the 14-pin version is such a great tip! So soldering the middle right 3 legs together and the middle left 3 legs together should be enough or do they need to be connected to ground? Sorry I am a newbie on this...

Also, I was wondering if you know of any circuit similar to the noisy cricket but for a bass guitar? Or like a Ruby amp with a bassman mode and tone controls but with the LM380?

Thanks again!

[PRR]

> do they need to be connected to ground?

They need to be well-"connected" to AIR, to pull the heat out of the chip. Some piece of metal. Look in the datasheet, they suggest a specific heaksink (which can't be found) and show dimensions. You don't need something that big or finny in most cases. I used to use small scraps of roofing-copper.

[hugcd]

Something like this, out of two small copper sheets?

[hugcd]

Sorry... I think its more like this:

[PRR]

Long thin leads don't carry heat well. The copper should butt right up to the body of the chip, where the leads are thick.

[hugcd]

Thanks PRR! Got it! There actually a lot of resources for the LM380!

I found this kit and its not that expensive. Maybe I could modify it for a bass guitar:

http://www.electronics123.com/kits-and-modules/2W-amplifier-module-LM380.html

Or I could try Mark Hammer's mini amp:



http://hammer.ampage.org/?cmd=lt&xid=&fid=&ex=&pg=3

Thanks again!

[R.G.]

The TDA2005, TDA2030 and LM1875 also make fine power amps that will work from small voltages to much larger ones. They can do upwards of 20W  if properly powered and heat-sunk.