I'm working through the book "TAB ELECTRONICS GUIDE TO UNDERSTANDING ELECTRICITY AND ELECTRONICS" and am about to order the components for the power supply the book instructs you to build. It calls for:

"(2) two 4400-uF, 50-WVDC electrolytic capacitors"

I have 2 of these in my shopping cart but wanted to ask here and confirm that these are the correct capacitors as they are quite expensive.

 

That looks like it will work but the price is LARGE!
I checked my favorite place and found similar prices in USA.
I could suggest you present the project here and we can see if there is a better way.

There is one on this page for less than half the price, but it is not-in-stock and not-in England. Point is, any voltage equal to or greater than 50 will work and you might find a winner by searching for any 4400 uf aluminum electrolytic from 50 to 100 volts.

http://www.mouser.com/Passive-Compo...0sq5zZ1z0sq5xZ1z0vhw6Z1z0sq5uZ1z0sq4iZ1z0vkuw

 

It doesn't necessarily have to be 4400uF; you could use 4700uF, or a couple of 2200uF's in parallel. 4400uF is not a standard value of capacitance, which is why they are so bloody expensive. 4700uF and 2200uF are common standard values; they will be much easier to find at far less cost.

 

Here is the schematic for the "dual-polarity, 34-volt raw DC power supply"

And later in the book this regulator will be added:

The parts list for the first schematic:

1 9 ϫ 9 ϫ 3 (w ϫ d ϫ h)-inch (or larger) metal
project box
1 Grounded (3-conductor) power cord
1 Power-cord strain relief
1 SPST 10-amp on-off switch
2 24-volt at 2-amp transformers (120-volt
primary)
1 3AG size (1ր4 ϫ 11ր4-inch) fuse block or fuse
holder
1 2-amp 250-volt slow-blow fuse
1 Locking terminal solder lug (see text)
1 6-amp, 200-volt PIV bridge rectifier module
2 10-kohm, 1⁄2 -watt resistors
1 three phenolic-type, 2-lug solder strips
2 two 4400-uF 50-WVDC electrolytic capacitors

And for the second schematic:

6 D1 through D6 1N4001 (NTE 116) general-purpose silicon diode
2 R1 and R2 1000-ohm, 2-watt resistor
2 R3 and R4 2.2-Kohm, 2-watt resistor
2 R7 and R8 470-ohm, 1ր2-watt resistor
2 R5 and R6 0.4-ohm, 5-watt resistor
2 P1 and P2 1000-ohm, linear taper 2-watt potentiometer
2 C3 and C4 0.1-uF ceramic disk capacitor
2 Q3 and Q5 TIP 31C (NTE 291) transistor
2 Q4 and Q6 TIP 32C (NTE 292) transistor
1 Q1 2SC3281 (NTE 2328) transistor
1 Q2 2SA1302 (NTE 2329) transistor
2 (Not illustrated) 3AG size (1ր4 ϫ 11ր4-inch) fuse blocks (optional)
2 (Not illustrated) 2-amp slow-blow fuses (optional)
3 Insulated banana jack binding posts (Radio Shack 274-661A or 274-662A or equivalent)
1 Universal grid board (Radio Shack 276-168A or 276-150A or 276-159A or equivalent)

you could use 4700uF, or a couple of 2200uF's in parallel

alright I will probably try this then. $100 for two components on my first real project just seems too risky.

 

Confirm. Now that the schematic is available I can confirm that the only requirement is that you have "enough" capacitance. You can piecemeal it together or buy a capacitor larger than recommended. No harm, no foul.

 

£2.73 each (plus p&p) in the UK from RS: 4700uF 50V electrolytic
Picture sows the wrong voltage, but it's just for illustration.

 

I hope heatsinks for Q1 and Q2 were called for in the book.

 

I can confirm that the only requirement is that you have "enough" capacitance

alright that's great news. I think I'm going to go with these: http://www.newark.com/jsp/search/productdetail.jsp?sku=55K2137

 

Looks good.

Send the money you saved to Allaboutcircuits.com
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Big City, USA
90210

 

Ole' Big City, USA. A place where the beer flows like wine and the beautiful women instinctively flock like the salmon of Capistrano...

 

Will this transformer work for the power supply? http://www.newark.com/jsp/search/productdetail.jsp?SKU=96F5529

 

That meets the specification in your parts list but...you might find a better deal on a 48 volt center tapped transformer rated at 2 amps.

http://www.newark.com/triad-magneti...nsformer/dp/28M9243?in_merch=Popular Products

 

0.4 ohm 5W resistors are a bit expensive as well. However, 0.2 ohm 3W resistors are cheap. Could I replace a 0.4 ohm 5W resistor with 2 0.2ohm 3W resistors in series? My thinking is that the voltage will be divided evenly between the two cutting the necessary power requirement for each to 2.5W.

 

That should work, yes.

 

.you might find a better deal on a 48 volt center tapped transformer rated at 2 amps.

Unfortunately I had already ordered the 2 transformers. They arrived and they are both already center tapped. Will this affect the design or function of this power supply?

 

No. You simply don't connect the extra wires.

 

Alright awesome that's what I assumed