Determining tantal cap. exactly?

Christ ! You're clueless !

Thank heavens we in the west have more brains than you Koreans. At least there's some hope for our jobs in the longer term.

Graham

"Eeyore" "Bob J."

** Phew - I just checked to make sure.

Thank god he is only South Korean.

....... Phil

Yes. Why don't you put 2 47uF, 6.3v capacitors in series and calculate what your new "compound" capacitor's capacitance and voltage rating is (assume ideal components). If you can't do this, you shouldn't have been tasked with this problem in the first place.

Depends on how precise you need to be... if you don't need more than, say,

+/-10% readings, just charge the cap to 5V, build something like a 1mA peak triangle constant current generator, and watch on a scope how the voltage changes as it integrates the current --> V=1/C*integral of I with respect to time + V0.

Too damn right mate !

Graham

--- I don't really understand your question, but if you're asking if it's OK to substitute a 22µF/10V cap for a 47µF/6.3V cap if you only need 22µF but you need the higher voltage, the answer is yes.

---

--- View in Courier:

12V-------------------+--------+ | | [10K] +---|--[10K]--+ | | | | ACIN>--[10µF]--[10K]--|----+--|-\\ | | | >-+-----+-------+ +-------|+/ | | |+ | | | [100µF] [CUT] | | | | |C1 [LM385-5] | [8k2] +->E1 +---->E2 | | | | | | | | [10K] [100R] | | | | |R1 GND>------------------+--------+---+-----+-------+---->GND

Set ACIN so that E1 = 100mV

Solve for the current in R1:

E2 I1 = ---- R1

Solve for the impedance of C1R1:

E1 Z = ---- I1

Solve for the reactance of C1:

Xc = sqrt(Z² - R²)

Solve for the capacitance of C1

1 C = ---------- 2pi f Xc

The error in the solution will be increased by the ESR of C1.

-- John Fields Professional Circuit Designer

John Fields:

Thanks a lot