Removing Neovibe power circuit

[bond]

is it ok to run both the lfo circuit and bulb off 15v? or do they need to be 2v higher than the rest?

[no one ever]

the lamp, i believe, runs off AC

[bond]

The secondary voltage is half wave rectified, which makes for a lot more work getting the ripple out of the supply voltage, and which I find an oddity, as diodes were not expensive even when the 'vibe was designed. I take this as an indication that lowest possible cost was a key design objective, and that there are other places that the maker may have cut corners.

The single diode feeds a first capacitor of 1000uF, to make about 22VDC which goes to supply the LFO section and the incandescent lamp. The LFO and lamp do not carry any signal, so any ripple in their supply is not a sound quality issue. After the first filter, there are two RC filters, with 100 ohm resistors feeding another 1000uF and finally a 100uF capacitor. This setup produces a well filtered supply of about 16VDC to the signal path. The actual voltage varies a bit, depending on the transformer, lamp brightness, and component tolerances.

In the clone of the 'vibe I built, I skipped the extra RC stages and simply took a 15VDC three terminal regulator from the first filter cap and supplied regulated 15V to the signal path. This saved quite a bit of board space and was actually cheaper than the cost of the caps and resistors. I believe that three terminal regulators were more expensive when the 'vibe was designed. The regulator is a trouble-free improvement.

the runs off dc's just it isn't regulated, so voltage fluctuates alot, i'm just curious if other people have run the circuit off lower voltages and succeeded, i may just have to build it like i want it and hope it works.

[R.G.]

It'll probably be fine on +15, as long as  you have enough current to run the bulb and not sag the voltage to the signal line as well.