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Voltage reduction

Andy Betts

i build guitar effects pedals for a hobbie, and I have a modification I'd like to carry out and i'm hoping some of you may be able to guide me with a solution.

 

Ok... Here's my plan. I have 2 effects pedals... An electric mistress which runs on 18v (it actually has a voltage regulator inside it with reduces the voltage to around 13v but it does run on 2 9v batteries), the second pedal is a boost pedal which runs a single 9v battery which i currently run after the electric mistress to boost the output. The problem with the electric mistress is when you engage the effect the output volume drops by around 10 to 15%, so the boost pedal compensates for that drop.

 

What i want to do is build the boost circuit into the electric mistress enclosure.. so the guitar will go into the electric mistress travel through the mistress circuit to the output of the circuit then into the boost circuit, then to the output jack socket. Simple, but i have a dilema inso far as they each run on different voltages, so how can i regulate the 18v DC down to 9vdc for the boost part of the circuit? If they both ran on the same voltage it'd be easy.... but i'm a little lost with this.

 

I've been told to use a resistor but I've also been told that's not the right way to do it.... Any ideas?

Parents

  • Blimey..... I leave, turn my back for a bit and there's loads of responses. You guys are just great.... Many thanks for your input on this.

     

    For those that are asking here is the schematic of the boost:

     

     

    image

     

    This schematic is the one I built on a blog post. The 500k rev log pot will be replaced by a trimmer as it will be inside the pedal enclosure. Once the output has been set that's it.

     

    The Electric mistress circuit diagram is here:

     

    image

     

    Just to set one thing straight.... Although the Mistress runs technically on 2 9v batteries this one if set up to run off a 18v power supply as there's physically no room in the enclosure for the batteries. I have effectively removed the battery snap from inside and installed a DC power socket.

Reply

  • Blimey..... I leave, turn my back for a bit and there's loads of responses. You guys are just great.... Many thanks for your input on this.

     

    For those that are asking here is the schematic of the boost:

     

     

    image

     

    This schematic is the one I built on a blog post. The 500k rev log pot will be replaced by a trimmer as it will be inside the pedal enclosure. Once the output has been set that's it.

     

    The Electric mistress circuit diagram is here:

     

    image

     

    Just to set one thing straight.... Although the Mistress runs technically on 2 9v batteries this one if set up to run off a 18v power supply as there's physically no room in the enclosure for the batteries. I have effectively removed the battery snap from inside and installed a DC power socket.

Children
  • in reply to Andy Betts

    The booster circuit will run fine from 18V. Increase R11 to 2k if the LED is too bright.

    As drawn the LED will use about 16mA with an 18V supply, way more than the circuit itself.

    The booster should have a decoupling capacitor (0.1uF to 1uF ceramic) across the TL061 pins 7 and 4.

    The TL061 is not the optimum chip of its type here, it's the low current version, use a TL071 for lower noise, it'll use a bit more current but nothing like as much as that LED !

     

    MK

  • in reply to michaelkellett

    Michael, as the boost will be built into the mistress enclosure i'll not be using the LED so the resistor is redundant

  • in reply to Andy Betts

    Hm ,,, I found both circuits in the websites under Goooooo
    You use these circuits?


    Well, the Boost amp can be easily operated with this V++ 13.5V after the voltage regulation.
    But above all else, the 18V could probably be used as a phantom power for a subsequent or pre-connected circuit. Is that so?
    Then you probably also have to pay attention to the circuit direction of the pawls.

    Yes, the TL071 would be a good alternative. But very low noise would not be the domain here.

     

    But if you want to tinker, then you can exchange the other ICs for more modern parts that need less power.

    For example, the voltage regulator can also be made cheaper with a 3-leg regulator instead of the 741 and Zener / transistor.

    The same applies to the 4-fold comparator and the NE4558, which are already very old gentlemen.

    So a good weighting of anything can add value to such a pedal.

     

    TL084 (4 OPAMPs in one housing) for all audio buffers, and the regulator (if you not like to change it to a 3-leg device), and the regulator feedback voltage

    as the reference voltage for the delay SAD1024 can be made cheaper.

    http://www.pmerecords.com/Docs/Archer_SAD-1024_Tech_Data.pdf

    The comparator can be CMOS version, so the 4013 D-FF would be optimal sourced with that. -> Fan-in / fan-out, the comparator resistors can be higher as well, it saves current.

    All in all the layout would also be a bit smaller as well mounted with SMD. Last but not least using a low current LED can save current as well.

     

    …. last idea: do you like to program an µC? so you can rebuild a mistress in digitally kind.

     

    Best Regards

    Gerald

    ---

    Attachments:
    imageSAD1024_Reticon.pdf