First off, Hi, and thank you for making such a cool pedal. I am using this project as my electronics lab project. Since I have full use of oscilloscopes, function generators, and various testing equipment, i thought it would be fun to poke around at various smaller components of your design and see if there is any room for improvement. As i am brand new to this, i was hoping you could help me out a bit. The first component i built was the power supply. I noticed you decided on the TC1044 chip, which was a very interesting little chip to use. So looking at this datasheet, http://www.kynix.com/uploadfiles/pdf8827/TC1044SEOA.pdf I find.. "Theoretical Power Efficiency Considerations In theory, a capacitive charge pump can approach 100% efficiency if certain conditions are met: (1) The drive circuitry consumes minimal power. (2) The output switches have extremely low ON resistance and virtually no offset. (3) The impedances of the pump and reservoir capacitors are negligible at the pump frequency. The TC1044S approaches these conditions for negative voltage multiplication if large values of C1 and C2 are used. Energy is lost only in the transfer of charge between capacitors if a change in voltage occurs. " Basically, it says if you use 100uF caps, you can obtain 100% efficiency. So my question is, would using 100uF caps in this design have any negative effect on the pedal? Further on down the page, i also came across this section, "Paralleling Devices Any number of TC1044S voltage converters may be paralleled to reduce output resistance (Figure 4). The reservoir capacitor, C2, serves all devices, while each device requires its own pump capacitor, C1. The resultant output resistance would be approximately: R out= R out(of TC1044s)/n(number of devices)" So running these chips in parallel will lower the output impedance. This, of course is mostly for academic curiosity, and i realize that a serious modification to the final pc board would be the result if it worked, but is this actually going to affect my overall sound when completed? I have a few more questions, but since they are not related to the TC1044 chip, I think i will just email you instead. BTW, the troubleshooting guide is a great focus on helping me test this project as i go, THANK YOU!!! Anyways, happy :guitarsg: :guitargibso and whatnot,
qbgjklssd wrote: > So looking at this datasheet, > http://www.kynix.com/uploadfiles/pdf8827/TC1044SEOA.pdf This is a "Selection Guide" - the original datasheet you are citing from is located at http://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf. > I find.. > "Theoretical Power Efficiency > Considerations > In theory, a capacitive charge pump can approach > 100% efficiency if certain conditions are met: Only if there is exactly zero load current and therefore no need to transfer any charge. Unfortunately, at this operating point the efficiency reaches 0%. There is no way to avoid the problem of the missing energy, known as "Capacitor Paradoxon". http://www.physics.princeton.edu/~mcdonald/examples/twocaps.pdf > Basically, it says if you use 100uF caps, you can obtain 100% > efficiency. So my question is, would using 100uF caps in this design > have any negative effect on the pedal? It will increase the time to reach the steady state condition. Initial power loss rises too. The LTspice example shows a steady state efficiency η=33% (@Il=500nA).
1 | p_in: AVG(v(v+)*i(v1))= -7.64875e-006 FROM 0.99 TO 1 |
2 | p_out: AVG(v(vout)*i(rl))= 2.49959e-006 FROM 0.99 TO 1 |
3 | eta: p_out/p_in= -0.326798 |
Feel free to improve it ;)
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