I’d like to homebrew a 5-V, 1-A dc power supply ...

Q I’d like to homebrew a 5-V, 1-A dc power supply that Ican use with a frequency counter as well as some other projects. Can you suggest something that’s compact, inexpensive and uses easy-to-find components?

A If you’re going to challenge the Doctor, you have to do better than that! But seriously, take a look at the diagram in Figure 2. This little 5-V supply should give you decent regulation. It meets your cheap-and-easy test, too.



Figure 2—This little 5-V power supply is simple to build and should supply up to 1 A of current. Make sure you put a heat sink on U2, the voltage regulator. RadioShack part numbers are shown below.

• C1, C2—0.01 mF, 2000 V ceramic disc capacitors (272-160)
• C3—1000 mF, 35 V electrolytic capacitor (272-1032)
• S1—SPST toggle switch (275-602)
• T1—120/12 V transformer (273-1352)
• U1—Bridge rectifier module (276-1146)
• U2—7805 5-V voltage regulator (276-1770)

From QST June 1999