neovibe and univibe difference...

[swt]

hi. i have a couple of univibe circuits, including an original schem, and the resistor going to the base of the bulb driver is 47k instead of 4k7 that the neovibe has. was this done to get more current or is just a typo??. or maybe the original were that way and the schems are wrong??. thanks for your help and insights..

[tcobretti]

On the schems over at GEOFEX, there is a 4.7k resistor on the base of the Lamp driver.





From  http://www.geofex.com/Article_Folders/univibe/uvfrindx.htm.

[SteveB]

The original calls for a 47k, & that is what R.G. had in the schematic when I built my clone in 1996. A bit later, he suggested changing it to a 4.7k instead.
I found that the 47k left me wanting a bit more, but the 4.7k gave me too much throb. I currently have a 10k in there.
Moving the LDRs closer to the bulb may minimize the throb.

Here is the schematic from the old Uni-Vibe manual. Sorry for the huge pic, but it's not mine, just from a link.


Steve

[swt]

that's the schem i'm using. i guess R.G wanted to have something corrected from the original, or at least made athat for the different transistors...i just wanted to know if it's better one or the other. thanks for the replies...
Also...is there a way to improve that oscillator or have a different one (better), or at least have higher and lower speed??.

[SteveB]

that's the schem i'm using. i guess R.G wanted to have something corrected from the original, or at least made athat for the different transistors...i just wanted to know if it's better one or the other. thanks for the replies...
Also...is there a way to improve that oscillator or have a different one (better), or at least have higher and lower speed??.

I say build it, & try each resistor so you can hear the differences.

I don't know about improving the ocsillator, but the slow speed is slow enough for me. For faster speeds you can lower the value of the 2 4.7k resistors in line with the speed control. If you do a search here on "Neovibe speed" you will find some posts about that. I lowered them to 2.2k which sped things up, but then soldered in some parallel, which lowered the value to somewhere in the 1.2k+ range. This gets the fast speed up in to the Leslie territory. I guess I could just remove the stack, & solder in single resistors, but it works as is, & I just as soon leave it as is.

Steve