Old(er) vs new(er) bench power supplies?

[codeboy2k]

Don't overlook the Power Design TP343A series. Years of use and the only items needing replacement are the VOLT / AMP switches and possibly a 10 turn voltage control pot.

These are all absolutely silent runners and are a pleasure to work with.

You can also get some individual Power Designs PSUs for $25 to $50 on eBay sometimes. So for $150 max plus shipping you might get 3 great (but individual) supplies.  Don't overlook this either.

There is an advantage to having individual supplies rather than 1 big one with multiple outputs.  If one supply fails you still have two others.  However, if something goes wrong in your triple output supply, you're down for a while.

[Gyro]

I don't have any knowledge of the BK but have a GPS2303 so can offer some inputs...

I don't see a cooling fan on the BK psu, just a couple of big heatsinks at the back (maybe internal or none? I don't see a fan exhaust). The Instek has internal heatsinks, and an internal fan blowing hot air out (kicks in as temperature rises). So maybe the BK will be quieter than the Instek. or maybe the cooling fan of the Instek is a good sign of longevity? But then again, the BK is only 2amps per channel + 5Amps (9A total), while the Instek is 3Amps per channel x 3 outputs (9A total) -- draw(?) or slight win for Instek because of the fan.

The large rear heatsinks on the BK should be rated for full load with just convection cooling, but will get very hot in the process. The internal heatsinks on the Instek are much smaller (surprisingly so and PCB mounted) and are completely reliant on the fan cooling and any reasonable load. Seems to work well in practice (seems bulletproof) but will obviously be noisier at high load, but much less at risk from blocked convection airflow (stacking books on top etc). The majority of the weight in the Instek is the big torroidal transformer, not cooling hardware. It also uses transformer tapping relays to minimise the heat disipation - you hear these click as the voltage is adjusted, again a sensible design idea and appears to work well without glitching.

More digits/resolution on the BK PSU LED display. BK for the win.

BK has coarse and fine voltage adjustments. The Instek needs light-finger touch if you want to set voltage/current to exactly 15.00 (so you don't get 14.99, or 15.01). BK wins.

The Instek has single turn pots, reasonably easy to adjust to 0.1V, very fiddly to get to 0.01V - ie. its display resolution is a reasonable match for setting accuracy. Don't know about the BK.

The BK only goes to 2 Amps on outputs A & B, the Instek to 3Amps on all outputs. Instek for the win.

The Series / parallel options are really useful on the Instek for getting lower voltage higher current, higher voltage lower current, or dual tracking supplies. The output terminals are automatically switched and the slave channel automatically follows the master to ensure equal voltage and current sharing. Of course you can connect them as you want for individual adjustment too. I doubt if the 3303 is designed for paralleling the 5V too to get 9A, but I suppose it might work if you adjust the other channels very carefully - not sure what would happen if you tried to pump 30V @ 6A into the 5V output  Nothing good at a guess 

Edit: I'd be surprised if someone hadn't tried that at school mind you!

[fivefish]

Right. Good inputs. Yes, the multiple tapping depending on your output voltage setting keeps heat dissipation at minimum required.

I'd be surprised if someone hadn't tried that at school mind you!

The 3 channels all have floating outputs, so technically, you can set CH A & B to 5V, parallel it with the fixed 5V output, and get 5V @ 9Amps (3A x 3 in parallel)... if you need that. 

Also have to add that the operation of the voltmeter and ammeter displays are totally separate from the PSU operation. i.e. your voltmeter and ammeter can be busted and the PSU will still operate normally (just have to use an external multimeter).  Replace the busted AD converter chips with a compatible ICL7107 (cost $0.60 on eBay) and you're back in business.

On the Instek, I've load tested the 2 channel outputs (A & B) at it's max operating Volts/Amps over 1+ hour continuous and it survived. No problems at all. --- actually, I was testing my DIY Electronic Load. Both my PSU and DIY Eload survived at 60V @ 3A, or 30V @ 6A.

I don't see a separate DC Outputs ON/OFF switch on the BK. So Instek for the win in this area.

I'm sure the BK can also do it, but I've also personally tried series operating (2) Instek units, to get 120Volts DC @ 3Amps, or 60V @ 6Amps.  No problems. 

[rastro]

I have both BK 1760 & HP 6236B.  They are both great linear supplies.
Pluses:
- Both are air cooled no fan noise.
- Schematics freely available on line.
- HP 6236B is fairly compact.
Minuses:
- HP 6236B has some audible 60Hz noise from the large transformer. 
- HP 6236B does not have adjustable current limiting feature - crow bar maximum current only.
- BK 1760 takes up a fair amount of room on bench compared to newer switch mode power supplies.
- Manual control only

With some patients you can find both unit on eBay for under $100.00

[Vgkid]

Another good option are Lambda power supplies.

[gsrokmix]

Well I decided to go with the Instek supply. I'll have a go with it & see how it is. It seems to get good reviews from what I've read, minus the single turn pots which people don't really like for their low resolution.

There seems to be no shortage of all of the older BK & other units out there, so if this newer supply doesn't work out for me, I'll start hunting again.

Thanks very much to everyone for their advice, I really appreciate it.

George

[JoeN]

I bought a GW Instek GPS-3303 power supply. All analog design, dual 0-30V, plus a dedicated 5V output, all 3Amps capable. I liked it so much, I bought (2) more dead PSUs on eBay for $50 each and for additional $10 in parts, fixed them all. So I have (3) of these GPS units in my lab, plus (2) HP power supplies (6205C, E3620A).

That looks a lot like the first power supply I bought.  Mine is badged Mastech-HY3005F but it looks the same, otherwise 30V 2 channels, one 5A channel, same parallel/series/independent switching, etc.  It's worked great for me over the last 3 years.  Got it for $200 and that is still the price.

http://www.amazon.com/Mastech-HY3005F-3Triple-Linear-Power-Supply/dp/B004ISD7T6 
http://www.testequipmentdepot.com/instek/powersupplies/linear-dc-power-supply-gps-3303.htm

Instek's 2303 model, you pay less because of the spelling error.  Actually, they even got the model number wrong.  I'm sure they fixed that by now.  Maybe that was an early image they sent to Amazon.  Still, I think it's funny.

[fivefish]

LOL That is funny. 

Anyways, the 3303 looks like this. No typos.


It may look similar on the outside, but the guts/internal design are totally different between Mastech and Instek

[JoeN]

Are those big LED driver ICs ICL7107s?  If so, Maxim, Intersil, Microchip or some unknown clone company?

[FlyingHacker]

I will second Lamdas as great starting supplies. I got a couple triple output LPT-7202-FM models. Sure, they have analog meters, but they are faster to note a change with (slower to read the exact values). They are very solid, and silent save for a hint of hum. I have one of units with two of the three supplies wired for auto-tracking so I get matching voltages for use as positive and negative supplies for op amp circuits. They are floating ground unless you connect the earth ground; so no ground loop worries. I got mine for around $35 plus shipping. I think they each had a broken binding post, which cost 20 cents and ten minutes to fix. The prices vary a lot, but if you look around you can often find them cheaper, or make an offer. Remember, you are getting three supplies in one. If they don't work, or put out less than rated current, I can tell you which capacitors you typically need to replace. Easy, through hole boards.

I also have one Acopian dual supply, which is nice, but having a single meter for volts and amps for each supply is really annoying, and possibly dangerous to your circuit. You want it on amps when you are testing things, but you also want to see that you have the volts set correctly. I would highly recommend your supply have a separate volt meter and ammeter.

You will really end up wanting at least two or three supplies, possibly more.

[fivefish]

Are those big LED driver ICs ICL7107s?  If so, Maxim, Intersil, Microchip or some unknown clone company?

It was a different part# (not 7107)... I can't remember anymore, the part# costs $25-$30 on eBay.

But I replaced it with an ICL7107 ($0.75) and it works the same.