5V to 170V Transformer?

I need a specific transformer to make 5V go up to 170V. It can be a little high and I can just use a potentiometer to lower it if needed. Where can I find such a specific transformer?

Since okorder

YOU MAY USE ANY TRANSFORMER PRIMARY WINDING HAS 110V X 2 AND SECONDARY WINDING HAS 5V OR 5V X 2. THIS IS A COMMON TRANSFORMER SOLD IN SHOP. JOINT THE 110V WINDINGS IN SERIES TO PRODUCE 220V.