0
\$\begingroup\$

I need to calculate the transformer VA for bipolar regulator circuit using LM723 so I need the voltage drop or may be a headroom for LM723 under load. The data sheet is silent about it. Is there anybody who had an experience building LM723 based PSU to answer this question?

Here is the schematic of circuit: enter image description here

\$\endgroup\$
2
\$\begingroup\$

The data sheet specifies a minimum input-output differential of 3.0V, so to that add Vbe for the emitter follower. 1V additional should be adequate up to a couple of amperes out, so figure on 4V.

\$\endgroup\$
  • \$\begingroup\$ Spehro! According to our discussions in my posts, here is what I got: Lets's say that I need 15V/2A from each rail. So I loose: MUR860 rectifier : 1.5Vx2; Regulator LM723 : 3V; MJE3055 emitter follower - 1V; Filter cap - 2V. Now: 15V/1.4141 = 11 (10,60745350399547) + 9V of losses = 20V + 15% (for line voltage brownout/dips) = 23V - the secondary voltage. Now current: 2A/0.62 according to pdf = 3.3A (3,225806451612903). So 23x3.3x2 = 151.8VA transformer. Is that right? \$\endgroup\$ – Roman Feb 16 '16 at 0:11
  • \$\begingroup\$ Do I have to make a new post for this question? \$\endgroup\$ – Roman Feb 16 '16 at 17:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.