neovibe bulbs blown

[rhdwave]

In the course of trying to get the right bias with the trimpot and then testing with the speed and depth pots i've now blown 3 bulbs.  I'm using the ones from smallbear, not the screw in types, but the ones with the leads.  The thing is, on one occasion i thought i had it dialed in, as the bulb was blinking well, had the speed up high as well as the depth and it looked secure, then all of the sudden it flashed a little brighter and poof! gone again.

I'm wondering if increasing the value of the resistor which goes just before the trimpot would help this.  I'm currently using i believe a 68ohm resistor.  I have adjusted the trimpot to where i get just the orange glow on the bulb with the depth all the way down, and can raise it all the way up to a good brightness, but then somewhere along the way it just goes. 

The other thing i've noticed, and i'm not sure if this is the way it's supposed to be or not, because i have not gotten any sound connected as of yet, is that the depth pot seems to do not very much for a large part of its rotation, and then all of the sudden increases the brightness very quickly.  I also currently have a 50k pot hooked up where R49 would go to try and adjust for this, but i have not seen that much of a difference in the way the light changes (slight but not much).  Again, i'm not sure how all of this will translate soundwise, as now i am waiting for another shipment of bulbs.

So i guess i'm just looking for some ideas here as to how to prevent the constant loss of these bulbs and also, if the light is supposed to behave as i have described?

With the depth all the way down and the speed as well, the light seems pretty steady and just glowing.  Has anyone used these bulbs before and if so have you run into the same situation? I'm thinking it's just my adjustments but i would love some feedback. 

Much thanks!!! 

[plankspank]

What are you using for a P.S.?  If you have a DVM, I would recommend you check the current draw of the circuit without the bulb (insert DVM in circuit instead of bulb). You should be drawing around 30 ma. Also measure R48 to make sure it is reading the correct ohmage (larger here wouldn't hurt). Perhaps you have a short from emitter to ground on the bulb driver.

[rhdwave]

Okay i will check all that.  I'm using a 15vac power supply that i got from mouser.

[wlrs]

You never said what type and voltage the bulb was this is important .. it really needs to be a 12 volt 30 mA bulb. If you start having problems with the transistor getting to warm do what I did and double it up.. I done this and now I have no more over heating problems..
Here is the ones I use
http://www.radioshack.com/product/index.jsp?productId=2102815&cp=&pg=2&sr=1&origkw=light+bulb&kw=light+bulb&parentPage=search

I take my knife and cut the shrink wrap off and unsolder the extra wire..Oh if you double stack the transistor you can use a 12 volt 50ma bulb with out the transistors getting hot ..
I also found out that if you use a 100K trim pot instead of r35 and r36 you can dial in the sweetest swirly sound. I also like to use at least a 500K volume pot the 100K seems to take away some of that swirly sound for some reason.
One last tip for yeah is if you can ! Try to use a glass in cased LDR's they also make a big difference in the sound again here is what I use
http://www.alliedelec.com/Search/SearchResults.asp?N=0&Ntt=VT33N2&Ntk=Primary&i=0&sid=473B8C001FDEE17F there a little pricey but worth the extra coins..I hope this helps U out man and may the tone gods be with you or at least a little lady luck..
Walrus

[RedHouse]

... I'm currently using i believe a 68ohm resistor....

I believe you've run into the other error in that PDF file, the original univibe actually uses a 150 Ohm resistor in that position, so yes, IMHO you should increase it, when at 150 Ohms you'll likely never blow out another bulb. I pointed out that R48 issue 4 or 5 years ago to RG, he has his own reasons for doing things and I'm sure he'll enlighten us why.

I now always use the correct 150 Ohm current limiting resistor in my vibe builds, and regardless of which bulb I use bulb-blowing does not occur anymore.

BTW, the bulb does not have to be 12 volt, I have experimented with 1.5 - 24 volt bulbs, as long as they are <100mA they work, although some bulbs have a strangness (time constant?) that makes the vibing sound different, more like a Phase 90 with less warble and more sway.

The Radio Shack bulbs work well, but kind of a hasle getting the leads out of the wrap and sometimes the remaining leads are too short to go through thicker PCB material. For a while I was using some 6 volt 40mA bulbs used in older Pioneer and Marantz lighted-dial stereo's which I got at a surplus outlet, they worked very well, lately I have been using some 14 volt grain-of-wheat lamps and am quite happy with them.

[R.G.]

I believe you've run into the other error in that PDF file, the original univibe actually uses a 150 Ohm resistor in that position, so yes, IMHO you should increase it, when at 150 Ohms you'll likely never blow out another bulb. I pointed out that R48 issue 4 or 5 years ago to RG, he has his own reasons for doing things and I'm sure he'll enlighten us why.

Sure. It's not an error.

Original Univibes used a variety of resistors there. 68 was common, as was 82, 120, and 150.

[rhdwave]

Okay, these are the bulbs i have been trying: http://www.smallbearelec.com/Categories.bok?category=LEDs+and+Lamps&searchpath=19445&start=9&total=9

After blowing two more bulbs, i decided to increase R48 to 120ohms...so we'll see how that works.  These bulbs are only 1.5V but 25ma...I have to say, if nothing else my desoldering and soldering skills are getting better with this build.

As far as the transistor goes...i did notice last night in testing that it was getting quite hot.  How would i double stack a transistor? Not sure what that means exactly.

I have still yet to get any sound out of the neovibe as of yet...been up real late every night trying to debug with little results.  The lfo is working as i can get the bulb to flash, but i've noticed as others have said that the depth pot and speed pot need to be quite high for there to be any response. 

[wlrs]

I don't like using those small voltage bulbs as you can see for your self they blow out to easy and there not hardy enough for stage use.The wheat bulb would be a good one to use but I have not used one it is cheaper for me to go to radio shack and buy the 12 volt one then to orderthe wheat bulb.. The bluze vibe was put in a wah wah pedal. I sent this to a guy in Oklahoma and he gigs with it 2 to 3 days a week and he has never had a moments problem out of it. It has a 12 volt radio shack bulb in it.
Good luck with your build and let use know how it turns out. her is the link to my photos so far.
http://s219.photobucket.com/albums/cc179/wlrs102/

[rhdwave]

wlrs, I think you may be right about those bulbs.  I'll let you know how it turns out.  Those are some great pics...are those the new boards from general guitar gadgets? They look great.  Was that a trimpot you had in the r35 r36 spot? How did you get that in there? I don't seem to have the room for one.  Also, one more question if you don't mind...I guess that's what you mean by stacking transistors    So do you just solder one to the other with the corresponding base, collector, and emitters matching up?

Thanks for all your help!

[RedHouse]

I don't like using those small voltage bulbs as you can see for your self they blow out to easy and there not hardy enough for stage use.The wheat bulb would be a good one to use but I have not used one it is cheaper for me to go to radio shack and buy the 12 volt one then to orderthe wheat bulb.. The bluze vibe was put in a wah wah pedal. I sent this to a guy in Oklahoma and he gigs with it 2 to 3 days a week and he has never had a moments problem out of it. It has a 12 volt radio shack bulb in it.
Good luck with your build and let use know how it turns out. her is the link to my photos so far.
http://s219.photobucket.com/albums/cc179/wlrs102/

Way cool transistor tester, I had one of those back in the 70's! Heatkit was a cool place there was a store in our town.

Was the board in the wah shell a DIY self-etch? it looks quite different than the other pic.

Nice job BTW.

Those LDR's are spendy! I've noticed the hermetically sealed LDR's are always more expensive than the normal LDR's
(I'll have to add that part number to my list)

[RedHouse]

Sure. It's not an error.

Original Univibes used a variety of resistors there. 68 was common, as was 82, 120, and 150.

Yeah sorry RG, I could have better described it as the other discrepancy.

I just meant the Shin-Ei schematic calls for a 150 Ohm resistor there, but in practice they quite likely used other values as is common in manufacturing.

[wlrs]

wlrs, I think you may be right about those bulbs.  I'll let you know how it turns out.  Those are some great pics...are those the new boards from general guitar gadgets? They look great.  Was that a trimpot you had in the r35 r36 spot? How did you get that in there? I don't seem to have the room for one.  Also, one more question if you don't mind...I guess that's what you mean by stacking transistor's   So do you just solder one to the other with the corresponding base, collector, and emitters matching up?

Thanks for all your help!

Thanks ..
The pedal build was my first neovibe and was a pain to build. Yes that is the new board from GGG and it is all love with this build. If you have the old style board you will have to use one of those small trim pots http://www.smallbearelec.com/Detail.bok?no=160 but the one I used is a 200K pot. The ones I used are pulls from an old VCR if I see where some one has thrown out an old VCR or radio I will pick it up and strip all the parts out it there is some good stuff that can be used for pedal build and such. I'm a penny pincher but I have buckets of old resistors  caps diodes and transistors. Its how I learnt to use a soldering iron.. but be carefull if you strip out TV's man allways let them set a week unplugged so it don't kill you 70,000 volt is a bad dude and it will jump 3 inches across to you if you are a good enough ground.
Most of the parts I used on the new neo vibe build are new.
Quote
I guess that's what you mean by stacking transistors    So do you just solder one to the other with the corresponding base, collector, and emitters matching up?
Yes sir..
but you have to leave one of the leads longer then the other because both wont fit in the holes.
Hope this helps U out.

RedHouse
I bought 2 of those off ebay for 10 bucks man and there a heaven sent as far as testing transistors go..The one in the wah wah shell is the old style GGG board. the new ones rock.. I had a dude come over yesterday who is a drummer and he loved the neovibe he said it was spot on to his guitarest real univibe.. COOL

[wlrs]

rhdwave
Hay man check the pc board traces real close and make sure there all thier the first board I built had one missing and after 5 days of checking everything I found that I had a pc board trace missing where Q1 ties into Q2.. just a thought. if you have a pc board missing as Jd if he can repalce it He did for me he is a real nice man to deal with ..
The
walrus

You guy's got my head swolen a little so I thought I would share a pic of my metro jtm45 build with yah it is my first amp build and I used all Vitamin Q caps along with carbon comps and domino pF caps I had them laying around so I tought it do the amp good and it did man those paper in oil caps sound alot better then the mustards that I used first time around.the amp has a murcury magnetic out put transformer the tube are siemens el34's and the pres are mullard and RCA.
Thanks.
Darrell AKA the walrus

[rhdwave]

rhdwave
Hay man check the pc board traces real close and make sure there all thier the first board I built had one missing and after 5 days of checking everything I found that I had a pc board trace missing where Q1 ties into Q2.. just a thought. if you have a pc board missing as Jd if he can repalce it He did for me he is a real nice man to deal with ..
The
walrus
Darrell AKA the walrus

Hey Darrell, thanks for the replies! As far as the pc board goes, i actually did the etching myself, so calling Jd wouldn't be an option (though that might be funny if i asked for a replacement board for one i etched myself), but regardless it appears that all traces are present.  I have sound now, but the vibe is not very much present like i have heard in other soundclips.  Also, there is a huge amount of noise.  I can hear the lfo through the amp, but it's more on its own rather than coming from the guitar signal...just kind of this pulse in the background (or foreground in this case). 

On a positive, i have not boxed this up yet, just have the board populated and the pots and some of the fine tuning elements like r35 and r36 into 50k pot on a breadboard.  So i'm hoping this is where all the noise is coming from, but i really don't think it's working right. 

[alfafalfa]

Walrus I read you replies and have a few questions .

Do you mean you use two trimpots, one for r35 and one for r36 ?
And the 500 k stereo neg log ?

Thanks, Alf

[rhdwave]

Walrus I read you replies and have a few questions .

Do you mean you use two trimpots, one for r35 and one for r36 ?
And the 500 k stereo neg log ?

Thanks, Alf

Hey Alf, i think this is actually something i can reply to...I'm pretty sure that Walrus means using one trimpot instead of r35 and r36.  What you do is: connect the outside lugs of the pot or trimpot to the sides of r35 and r36 where they don't meet. In other words, instead of r35, use one outside lug to connect to that pad and instead of r36 use the other outside lug.  Then connect the wiper to the junction of r35 and r36 on the other side.  I think, if memory serves me this will be the same thing as the n pad on the board.  My problem with this was that i couldn't get a trimpot to fit there.  Currently i'm trying as R.G. had suggested and i have two 82k resistors (one for r35, one for r36) each are hooked to the outside lugs of a 50k pot and the wiper is connected to the n pad. 

The other trimpot is already factored into the board...it's the bulb bias adjustment. 

[wlrs]

Walrus I read you replies and have a few questions .

Do you mean you use two trimpots, one for r35 and one for r36 ?
And the 500 k stereo neg log ?

Thanks, Alf

Hey Alf, i think this is actually something i can reply to...I'm pretty sure that Walrus means using one trimpot instead of r35 and r36.  What you do is: connect the outside lugs of the pot or trimpot to the sides of r35 and r36 where they don't meet. In other words, instead of r35, use one outside lug to connect to that pad and instead of r36 use the other outside lug.  Then connect the wiper to the junction of r35 and r36 on the other side.  I think, if memory serves me this will be the same thing as the n pad on the board.  My problem with this was that i couldn't get a trimpot to fit there.  Currently i'm trying as R.G. had suggested and i have two 82k resistors (one for r35, one for r36) each are hooked to the outside lugs of a 50k pot and the wiper is connected to the n pad. 

The other trimpot is already factored into the board...it's the bulb bias adjustment. 

I could not have said it better my self ..
Thanks
Darrell AKA walrus

[alfafalfa]

Thanks , guys , that's what I needed to know .

I'm going to try it straight away !

Alf

[wlrs]

You said something about it making A/C hum there is a way to get around this . If you get a danelectro wall wart open it up and change the LM7809 for a lm7815 you can use it instead of the ac wall wart you can then by pass the bridge rectifier as well if you want. Just take note as to witch way the + and - is on the rectifiers output or I'm sure you can leave it..
One other thing that will make it buzz and so forth is that its is not in a enclosure... If you have the board laying out on the table and not in a aluminum enclosure it will hum buzz and so on.. taking a piece of wire and stripping the ends back / you can loosen up the guitar cables going into the neovibe jacks put the wire in there and gently tighten it up snug this helps lose the buzz or humming that you are getting..
I hope this helps man and if you need anything else just make a post here I will be checking back from time to time..
as far as ask JD for a new if you made your own I'm pretty sure he keeps track of who he makes sales to + he is a nice guy and a catholic
he would probably rather give you one then U try to beat him out of it I wouldn't know for sure as I have never ask him.
Let us know how it turns out.
Walrus.

[rhdwave]

You said something about it making A/C hum there is a way to get around this . If you get a danelectro wall wart open it up and change the LM7809 for a lm7815 you can use it instead of the ac wall wart you can then by pass the bridge rectifier as well if you want. Just take note as to witch way the + and - is on the rectifiers output or I'm sure you can leave it..
One other thing that will make it buzz and so forth is that its is not in a enclosure... If you have the board laying out on the table and not in a aluminum enclosure it will hum buzz and so on.. taking a piece of wire and stripping the ends back / you can loosen up the guitar cables going into the neovibe jacks put the wire in there and gently tighten it up snug this helps lose the buzz or humming that you are getting..
I hope this helps man and if you need anything else just make a post here I will be checking back from time to time..
as far as ask JD for a new if you made your own I'm pretty sure he keeps track of who he makes sales to + he is a nice guy and a catholic
he would probably rather give you one then U try to beat him out of it I wouldn't know for sure as I have never ask him.
Let us know how it turns out.
Walrus.

Thanks Walrus! I will try that to get rid of the humming.  As far as getting a board from JD, i was completely kidding as i didn't buy it from him in the first place.  I would never do something like that.  But, i will definately keep you posted.  I really appreciate all the help!!!