https://www.google.co.th/search?q=capacitance+meter&biw=1097&bih=548&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjGyMybiNXQAhWGsY8KHb4aA0YQ_AUIBigB#imgrc=U5aisXRkmL8c_M%3A