Can anyone help me check why the inverter circuit I built outputs only 165 V at no load instead of the proposed 230 V. It can't even light a bulb because of that. I tried adjusting values of filter capacitor but output remained low.

The inverter circuit and output voltage wave is attached. I'm using a 12 V battery, Arduino Uno, IR2110, and a centre-tapped transformer. I notice that each time I switch on the inverter at no load, the battery terminal voltage drops from 13 V to 12.4 V. I think that voltage is still OK to get about 230 V at output.

Is my circuit and components I used OK? Please your suggestion will be highly welcome. Thanks.

NOTE: The scope trace is inverter output voltage which I measured through a 230v/6v step-down transformer. I expected it to give 8.48v peak (equivalent to 6v RMS), but it rather gave about 6v peak.

Arduino Uno-based inverter

output voltage with 0.47uF filter


I suspect that you are under-driving the low-voltage primary.

That 12-0-12 rating on the low-voltage side is the RMS value of the AC. The peak voltage, when used as a regular mains transformer, will be \$ 12\sqrt 2 \$. Since you are driving it with a peak of 12 V then the output could be expected to be \$ \frac {230}{\sqrt 2} = 162 \ \text V \$ which is very close to your reading.

You need to increase the turns ratio by \$ \sqrt 2 \$. An 8.5 - 0 - 8.5 transformer would be ideal.

  • \$\begingroup\$ What are your thoughts on the waveform being 6 Vpeak? Would you not expect it to be 12 V? \$\endgroup\$ – C. Lange May 28 '19 at 19:27
  • \$\begingroup\$ What voltage is 6 V peak? I see a photo of an oscilloscope trace but it has no caption so I don't know what it means, where it was measured and under what load conditions. (Hit the edit link under your question and fix it up ... Can we rotate the schematic while we're at it?) \$\endgroup\$ – Transistor May 28 '19 at 19:42
  • \$\begingroup\$ Thanks for your suggestion, quite useful. I tried using 8-0-8/230V transformer (8.5- 0 -8.5/230V transformer not available), and I got about 230V RMS output from the inverter. NOTE: The scope trace is inverter output voltage which I measured through a 230V/6V step-down transformer. Scope now reads about 6.04V peak which is equivalent to over 230V RMS inverter output. However the problem I have now is that inverter cannot light a bulb. When placed on 26W load (CFL bulb), inverter output voltage drops from 230V to 44V. What could be the cause of this? Your suggestions will be appreciated. \$\endgroup\$ – Emmanuel May 31 '19 at 11:15
  • \$\begingroup\$ "The scope trace is inverter output voltage which I measured through a 230V/6V step-down transformer." Well how were we supposed to guess that? Add a caption to the photo. You'll have to do more debugging. Post numbered, captioned photos (in your question) of the transformer input off-load and on-load. What about rotating the schematic? \$\endgroup\$ – Transistor May 31 '19 at 11:20

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