This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Wednesday, August 26, 2015

BigFoot Fx MagnaVibe

The MagnaVibe is a vibrato effect inspired by the built in effect on old Magnatone amplifiers. From the BigFoot Fx description:

The Magnavibe was inspired by the early 1960's vibrato guitar effect (not the typical tremolo which is just pulse modulation). The Magnatone amp was known for having that amazing wobbly sound. Setting out to put that type of sound in a box and use it with any amp took much experimenting. The results are excellent. This is not a plain one dimensional vibrato such as a chorus pedal with the dry mix removed. Delay chips weren't even used back then. Nor is it just another uni-vibe clone, but a unique sound with that classic unique tone. Adding spring reverb or delay after the vibrato sounds especially good.

I've drawn it so there's space to use a VTL5 or similar photocell, or you can make your own. Either way, theres space for it. A lot of layouts I've seen don't allow for a comfortable enough space to get the LDR and LED lined up nicely. You might even be able to get this to fit in a 1590a.


  1. How are we supposed to print out the toner transfer the correct size? Would it be possible for you to add a scale or even better, a PDF 8.5x11 that we could use to print?


    1. Way ahead of you. Click the tab at the top of the page called "Transfer Image Library" and look in the "Misc" folder. Check out the "General Layout Notes" tab for more info too.

    2. Well then excuse me! You sir are awesome! Keep up the great work!

    3. No problem. Let me know how your build turns out!

  2. is there anyone here who built this and verify it as working?

  3. what's the value for ldr and color and size of led?

  4. This one is verified. Start with a 1M dark LDR and a 5mm red LED. Not a bad idea to socket those 2 components though.

    1. i built this one and works fine.. but the vibe is not that good maybe it's because of the ldr and led i use.. i'll try to use you're recommendation though.. thanks anyway.. =)

    2. The PCB is perfect.
      I've breadboarded before boxing and the sound was pretty close to the original. 5mm red LED and LDR (unknow specification). After putting it into the enclosure I missed some intensity, mainly when the knobs are at maximum. Maybe it's the insulating tape wrapping the Led and Ldr, maybe the position of both. Trying another one soon.
      Thanks again, dtgehrin.

  5. thank you very much, Sir
    Really beautifull work

  6. This comment has been removed by the author.

  7. Can it slower speed increasing the pot value to 50?

  8. Sounds great!
    Some suggestions:
    - 470nf caps for more speed, and 2.2uf for slower speed instead 1uf in both caps under the transistor.
    Polarised or not, the same: I put 470nf and swith to add 1uf in parallel to have both speed ranges.
    - BC548 or 2N3904 works fine.
    - Cut trace between 100nf cap and the LDR, and put there 10k pot as variable resistor to get more tremolo like wave.


  9. If i put a mix control(dry signal) can i get kinda chorus effect?

  10. Hi,
    is somedbody can tell me if a VTL5C3 can be substituate to the VTLC5C2 ?


  11. ok thanks...
    it look like to be easy to make one ... But i would like to be sure about two points :
    - What is the best color of led ?
    - is there any space between the led and LDR or need to touch both ?


    1. Google to see what other people have used. They don't have to touch but should be pretty close. With LDR/LED combos there's generally a good bit of experimentation.

  12. Hi David,

    ok … i saw video in google but nothing about the distance ... pretty closed like 0,2 mm / like 0,1 inch ? I am to try no problem ... on google one people speak about white clear led and here one speak about red so ...

    And what do you mean by combos ?

    1. Just whatever combination of led and ldr you use. When I build things like this, I put the LDR right up against the top of the LED and then wrap it in headshrink so so excess light gets in.

  13. Ok David … many thanks for all …


  14. Hi David,
    is it easy to ad tap tempo ?

    1. No. You’d have to redesign the LFO with a microcontroller

  15. Made pcb and It sounds amazing! Thanks!!!

  16. i have a very pronunced volume drop. any suggestions?

  17. I made two and have a low intensity of effect, i change down the resistor in serie with led, change led and ldr, but aways with very low intensity, any suggestion???

  18. I can only head clean signal no effecr

    But i can hear the speed and intensity changing from a small noise. That is reaccting to pots

  19. Magnavibe Mods

    1. More or less modulation effect.

    Change 100nf capacitor value for more or less modulation. 220f gives more modulation, 10f give very mild modulation.

    2. Faster of slower effect.

    Change the 1uf electrolytic capacitor for a larger value to slow the speed of the effect, or a smaller value for more speed. You only have to change the 1uf that is in direct contact with the LED.

    You can add a switch in place of the 1 uf to switch between different values for a slow/fast switch.
    For example, 1uf for fast and 4uf for slower. You can use different values, or just switch multiple 1uf caps in parallel. example: 1uf + 1uf in parallel equals 2uf. 1uf + 2uf in parallel equals 3uf. etc.

    3. Turn vibrato into tremolo effect.

    Change the 100n capacitor for a resistor to turn the vibrato effect into a tremolo effect.
    between 1K and 20k ohms work, 1K being very very exaggerated effect (more like a heavy volume swell) and 20K give very very mild tremolo effect. I find 10K ohm to be a perfect.

    Change the resistor for a 10k or 20k linear pot. This allows you to change between very heavy and very mild tremolo effect. Any higher than 20K and the effect goes from heavy tremolo to dry guitar signal. 20K is hardly any vibrato anyway. The pow will set the tremolo’s intensity.

    The depth and speed knobs are shared between tremolo and vibrato.
    Depth is more a “mix” knob.

    4. Add switch for vibrato AND tremolo effect in 1 box.

    You can take out the 100n capacitor, and add wires in place. Connect these wires as the in and output of a on/on switch. Add 100n (or value of your choice) to one side of the on/on switch, and a resistor of choice to the other side of the switch.

    This allows you to switch between vibrato and tremolo

    Change the resistor for a 10k or 20k linear pot. This allows you to change between very heavy and very mild tremolo effect.

    The speed and depth pots are shared for both effects.

    5. Tremolo, vibrato, chorus switch.

    Use a on/on/on switch.

    Add the 100n cap to 1 position for vibrato.
    Add the resistor or tremolo pot to the other position for tremolo.
    Add 100n cap AND a 50k resistor in parallel for chorus.

    I tried a 50K resistor which works fine. The chorus effect isn’t very strong but its a bit different that just vibrato.


    The mini switch pop’s when switching between tremolo/vibrato/chorus.
    Haven’t been able to resolve this unfortunately.

    6. You can add a LED in parallel to the LED that is connected to the LDR, this led acts a speed/depth indicator. I think you could use this led as the fx on/off led.

    1. Works for this layout.

    2. I also experimented with the speed controls. The 1uf cap does fast to very fast settings. You can add 5uf parallel to the 1 uf cap for a total of 6uf. the slowest setting the 1uf cap does is similar to the fastest the 6uf cap.

      This way you'd only need a 2 position switch to have access to very slow/very fast settings.

      I tried 10uf as a largest value but that did NOT work.
      I assume 8uf would be the max that works, though I only tested 6uf max.

      Another mod I tried which is usefull.

      In place of the 100nf capacitor, you can add 2 wires. connect 1 lead of the 100nf cap to 1 of the wires, and then that wire goes to lug 3 of a pot.
      connect the other wire to lug 1 and 2. Add a 10nf cap to lug 1 and 3.
      I tried a 250k lin pot.

      This works as a vibrato intensity control, pot to control more or less modulation.
      Similar to how the 10K/20K lin pot for the tremolo mod works to give more or less tremolo effect. IMO this intensity control works better than the original depth control does.

    3. ok 1 more... LOL

      For slower speed the easy way.

      Take out the 27k resistor that is in parallel with the 25k speed pot.
      This makes the speed control a little slower, but the fastest speed stays the same.

      For even slower you can change the 25k pot for a 50k pot, though the 50 K pot is a tad too much, 40K seems to be the sweet spot.
      Take the 50k pot with a 200k resistor in parallel (equals 40k).
      At 50K pot the led stops flickering for some reason.

    4. Thanks for all of the info. Put one of these together over the last few days, and like a few others have mentioned the depth of the vibrato doesn't go very far. I'm guessing this is supposed to be a subtle effect. So I tried replacing the 100nf cap with 220nf as suggested, but no noticeable change. Went up a bit to a 270nf, again nothing. Is there another component value that needs to be changed along with the 100nf -> 220nf?

  20. Hi, built it, it works, but vibrato is very weak, i can hear it a little bit on the max pot value, tried 1m, 5m ldr, changed led - not much difference, transistors are mpsa18, can anyone know what do with this?