How to make 1-5 V to 4-20 mA Converter

Please describe briefly to me the 1.5 V to 4-20 mA converter. Also, please give me schematic of it.

I tried on an op-amp but was not satisfied of the output. I'm using LM741 op-amp, Vcc=12 V, R1 = 250 Ω, Rf =1 kΩ as shown in the circuit below.