coil voltage calculator
Calculate coil voltage for DC and AC coils from resistance, current, inductance, and frequency. Handles V=IR, impedance, and induced/back-EMF estimates.
coil impedance calculator
Voltage of a coil can be found using simple formulas: V = I*R in DC and V rms = I rms * Sqrt[ (R ) 2 + (w L ) 2 ] in AC and V L = L( dI/ dt ) to approximate transient/back-EMF spikes.
Formula & Table Summary:
- DC: V = I × R
- AC: ω = 2πf, Z = √(R² + (ωL)²), V_rms = I_rms × Z
- Transient: V_L = L · dI/dt
- Power loss: P = I_rms² × R
Units: V (volts), I (A), R (Ω), L (H), f (Hz). Add protection (diode/snubber) for inductive loads.
coil current to voltag
A Coil Voltage Calculator calculates the voltage across coils in terms of DC (V = IxxR), AC using impedance V rms = I rms x and transient/back-EMF (V L = L dI d t ). Use it to estimate heating (P = I 2 R), size drivers and predict spikes.
coil resistance voltage
| R (Ω) | I (A) | L (mH) | f (Hz) | Calculation | Voltage (V) |
|---|---|---|---|---|---|
| 2.0 | 1.5 | — | — | V = 1.5 × 2.0 | 3.00 |
| 5.0 | 0.5 | 10 | 1000 | ω=6283; Z≈5.00; V=0.5×5.00 | 2.50 |
| 1.2 | — | 10 | — | V_L = 0.01 × 1000 (dI/dt) | 10.0 |
Frequently Asked Questions - coil voltage calculator:
How do I calculate coil voltage for DC?
Use V = I × R, where I is steady current and R is coil resistance.
How to calculate coil voltage for AC?
Compute Z = √(R²+(ωL)²) with ω=2πf, then V_rms = I_rms × Z.
What is back-EMF in coils?
Back-EMF is the induced voltage V_L = L·dI/dt generated when current changes in the coil.
How to estimate transient spikes?
Use V_L = L·dI/dt with worst-case dI/dt; include supply and clamp voltages for total stress.
What units should I use?
Use volts (V), amperes (A), ohms (Ω), henries (H), hertz (Hz), and A/s for dI/dt.
How to size a driver voltage?
Use V_rms from impedance at operating frequency and allow margin for back-EMF and driver headroom.
Does inductance always increase voltage?
At AC or during transients, inductance increases impedance or causes induced voltage; steady DC sees only resistance.
How do I reduce back-EMF spikes?
Add flyback diodes (DC), snubbers, RC networks, TVS diodes or active clamp circuits.
How to calculate coil power loss?
Use P = I_rms² × R to estimate resistive (I²R) heating losses.
Can I measure coil resistance easily?
Yes — disconnect the coil and measure DC resistance with an ohmmeter; use low-current meters for low-resistance coils.
