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cGil

Bored silly

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how about a treadle?

you know, like an old sewing machine.

You just keep that sucker rocking until you put out enough juice... no battery needed!

 

you kids nowadays. you're so lazy!

 

You ever try to light up a set of 6L6's with a mule on a turnstyle?

I bet you haven't!

But back in the day, we thought nothing of it.

 

Why, when I was but a child, I hooked up my dano amp in case to my bike headlight charger and rode sixteen miles to a gig, playing

louie louie the whole way.

Wasn't even tired.

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I thought golf carts were for learning to drive intoxicated! Also good for doing donuts on the greens, getting airborne over the tee-off ramps, and crashing in the roughs... at 2am. But if it ain't got dangerously sharp blades spinning underneath, you're really missing half the fun! 8-[

 

Okay, gang, here 'tis. Almost. As you may be able to tell from the pics, only the power supply remains to be connected to the power/off/standby switch. Gotta pick up some power plugs and jacks at Rat Shack on my way home from the VA tomorrow. Then I'll fire this puppy up and take her for a spin. Don't ya just love a good cliffhanger! ](*,)'

 

MicroWatt-Spaghettified2.jpg

MicroWatt-Spaghettified.jpg

MicroWatt-TreasureChest2.jpg

MicroWatt-TreasureChest3.jpg

 

Gil...

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Am I allowed to use the term - BAD ***!!!

Who knew I would get excited tubes and knobs?

I have a tech guru that is friend and was part of the design process for many US bombers and fighter jets. He is also a lipo expert. I'm going to get his input on the best battery options for this.

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Well, now I'm pissed. Stopped by Rat Shack and picked up some plugs and jacks. What junk! One jack had a center lug that couldn't be soldered, and only melted the surrounding insulator/support gasket. #-o

 

So I got frustrated, pulled the whole ugly mess, and hardwired the battery packs to the switch. Okay, so it's alive, but it's got kaaraaaazy gremlins. One tube only works if I wiggle it around in the socket! And when it kicks in, there's some horrendous oscillation and blocking distortion going on at 11 that makes a strat sound like a fart getting strangled. Probably just a rushed solder joint. Or one I totally forgot to solder. Who knows!

 

Anyway, it's NOT loud at all with 63v on the plate using an inefficient 96/db/w/m Jensen P10r. Still not much louder with a 98db/w/m greenback. I'll try something more efficient tomorrow like a vintage 30 or alnico blue when I have some time to get into some serious chopsticking. But it's alive! You could talk over the buzz and oscillation without raising your voice. It also has a nice ring when I tap the preamp tubes, so it is fairly microphonic. Ordinarily I'd pull a 12ax7 tube that did that; but that's the nature of these directly heated cathode tubes, so I don't think it'll be a problem unless the amp sits on top of a speaker cab. At any rate, my ZVex Nano is so much louder that it could easily blow this amp's doors off in a street jam session, without even breaking a sweat. Apparently there's a HUGE difference in loudness between 1/10w and 1/2w . But then, a lot of guys with Nano's are always posting questions to ZVex about attenuators so they can use it as a bedroom amp. Go figure. This puppy might be a decent bedroom amp from the get go if the right iron could be found to suit it.

 

Oh yeah, I was waaaay off on Rat Shack's battery prices. I can get Rat Shack's D cells for a buck, but their 9volts are $10 per 4 pack. Guess I'd better check prices at Wally World. I think rechargeable batteries may be the far more rational option. I was looking for 7.4v to 48v batteries on the web earlier, and woah! There are lots and lots and LOTS of battery option!.

 

Some of those bigger 48v batteries are pretty darn expensive. We're talking $300! Even the hundreds of different 7.4v Li-Po's to choose from are all over the place in both price and milliamphour rating. But the research on the amp's power usage indicates that an amphour rating higher than 400ma isn't necessary for this thing unless you need it to run for more than a couple days per charge. I figure 9v batteries would be great for the beach (less to carry), but a bank of cheep motorcycle batteries would probably keep it blasting for weeks during a power blackout. Maybe I should look into solar cells and wind generators! :-&

 

Gil...

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I'm going bonkers waiting for SEwatt to come back online so I can get back to the fun of finding new ways to void all my Epiphone warranties. I think it's really beginning to get to me. Everything looks real short. Like the thread list. I was sure there was a thread around here somewhere that mentioned battery powered amps. Must've fallen off the edge of page 2 or something.

 

Anyway' date=' I mentioned this possibility... http://www.pentodepress.com/receiving/street-musician-amp.html

 

As soon as I found out how CHEEP those tube are, the bug bit me.

 

[img']http://i166.photobucket.com/albums/u103/cgil155/MicroWatt-RawTop.jpg[/img]

MicroWatt-Heaters.jpg

 

Gil...

 

Gil,

 

This sewatt thing is killing me. I don't know if you remember, but I started the "very basic build" thread over there. You guys talked me into getting the VJ. Well, I have had it for a bit now. I am going crazy waiting for sewatt to get back online. I thought I would give it a shot over here, but there just isn't anywhere near the info over here. The amp is quite nice sounding for a little over 100 bucks. I was very suprised. I am running it through a weber blue dog, so I am sure that helps a lot. The thing is still sittin there begging for me to do something to it. I just don't know where to start. Argh, I might just go crank up my mesa and take out some frustrations.

 

-Dave

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Hmmm. When I read "wind generator" my mind conjured a picture of the priest in Caddy Shack, out on the golf course in the storm, only wearing a propeller topped beanie cap powering a wall of Pignoses.

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LA

I have a nice off the beaten path tech question for you. I am all into amplifiers right now since I do RC almost all day long.

We are building a mini guitar amp and I suggest Lipos for power. Here is what the build is needing:

Here is a link:

http://forums.epiphone.com/Default.aspx?g=posts&m=59127

 

and related text below:

 

---------------

The lithium polymer battery idea sounds interesting. What voltage are they? NORMAL "RATED" VOLTAGE IS 3,7 VOLTS PER "CELL" SO, A 3 CELL PACK PUTS OUT 12.6 VOLTS AT FULL CHARGE, BUT IS RATED FOR 11.7 VOLTS UNDER LOAD.

How many recharges can they take? NORMALLY BETWEEN 300, AND 500 CYCLES

Do they get senile with charge-memory problems? NO, AND THEY DONT SELF DISCHARGE LIKE NICADS DO!!! etc., etc. I was considering scrounging up five or six kiddie cart 12v gel cells for extended camping trips or whatever, but was thinking three 24v batteries would probably be even better. HOPE YOU HAVE A STRONG BACK!!!

72v to the plates would probably make that sucker sing! We'll see. FOR 72 VOLTS IN A LIPO PACK, YOU WOULD NEED 19.5 CELLS IN THE PACK, SO YOU COULD SHOOT FOR 19 CELLS FOR 70.3 VOLTS, OR 20 CELLS FOR 74 VOLTS.

 

DO YOU SUPPOSE AN 18 CELL PACK, WOULD RUN THE SYSTEM??? THAT WOULD GIVE YOU 66.6 VOLTS. TO CHARGE THIS, YOU WOULD NEED TO BREAK IT DOWN INTO SMALLER PACKS OF EITHER (3) 6 CELL PACKS OR (2) 9 CELL PACKS. THE 20 CELL P ACK COULD BE MADE UP OF (4) 5 CELL PACKS, OR (2) 10 CELL PACKS. CHARGERS ARE AVAILABLE FOR EITHER OF THOSE SMALLER PACKS CONFIGURATIONS.

 

The heater at 1.5v is another issue. I could string all the tubes in series if there was a 7.5v battery. Not much chance of that I guess. The power pentodes can be configured for a 2.7v heater supply, but that would only bring it up to ~10v. But! If I add another preamp stage, it'll be a ~11.5v heater requirement! IN THE MODEL AIRPLANE BUSINESS THEY USE A DEVICE CALLED "AN ULTIMATE BEC" WHICH REDUCES THE VOLTAGE OF THE POWER PACK (UP TO 45 VOLTS) DOWN TO 5 VOLTS FOR THE RECEIVER. I KNOW THE GUY WHO MAKES THOSE DEVICES, AND I AM PRETTY SURE HE COULD MAKE ONE TO DROP THE OUTPUT VOLTAGE EVEN FURTHER. SAY 1.5 TO 2 VOLTS. WHAT I WILL NEED TO KNOW IS HOW MANY AMPS DO THE HEATERS PULL???

 

AT THE PRESENT TIME, THE BIGGEST "SINGLE CELL" LIPO MADE IS A 6000 MAH CELL. TO DO ANY ADDITIONAL CALCULATIONS I WOULD NEED TO KNOW WHAT THE TOTAL AMP DRAW OF THE AMPLIFIER IS. I WOULD HAVE TO HAVE THAT BEFORE I COULD CALCULATE THE APPROX RUN TIME FOR A PACK COMPOSED OF 6000 MAH CELLS.

 

OF COURSE, YOU CAN WIRE PACKS IN PARALLEL TO INCREASE THE STORAGE CAPACITY OF THE TOTAL PACK.

 

AS FOR WEIGHT, A 5 CELL PACK OF THE 6000 MAH CELLS WEIGHS 21 OZ!!!

 

GOT TO RUN NOW. LET ME KNOW IF THIS IS ENOUGH TO HELP.

 

L.A.

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The amp article mentions 250ma draw for the heaters, but the data sheets say it'll have a 350ma load on that 1.5v D-cell. The heater current draw may be as high as 2 or 3 times that during start up, so the heaters are, as usual, the real current hogs of the whole amp. An alkaline D-cell was tested to last 16 hours.

 

The article claims the plate supply probably has less than 9ma draw on it. Not sure if that was from just one tube, or all. But there are 5 tubes, so I would fudge that and pretend it needs 50ma, and then double it to 100ma just for the hallibut of a typical startup current draw, and go from there.

 

Gil...

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Meanwhile, back at the bench (finally!) I discovered the expected unsoldered ground on the heater of the third preamp stage. I also screwed up in thinking I had soldered the volume pot a little wacky cuz I just couldn't see where the wires crossed under the turret strip. I clipped a wire only to realize I had done it right the first time, so I put it back where it was. The bad tube socket in the second preamp tube is the next thing to fix. The tube only works if it's barely sitting in the socket for some strange reason, and the pin holes are too small to get a poker in there to re-tension it. I'll get to that after dinner. The remaining problem is the blocking distortion, but a quick voltage divider before the volume pot should take care of that.

 

Gil...

 

cc: PPwatt

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