A hard to resist problem

[throbscottle]

I reached this thread tool late to contribute to the multimeter choosing - I would have said try to get a Brymen meter. Still loving the one I got in July

 

[Justin Verrall]

I reached this thread tool late to contribute to the multimeter choosing - I would have said try to get a Brymen meter. Still loving the one I got in July

Just checked them out and there a little to pricey for me but they look really good

 

[spec]

Hmmm... Power supplies are a bit pricey but I think I'll either go for this one https://www.jaycar.co.nz/Power-Prod...t-Switchmode-Laboratory-Power-Supply/p/MP3800 as it's cheap but it's also variable or this one https://www.jaycar.co.nz/Power-Prod...ted-Variable-Laboratory-Power-Supply/p/MP3086 As it seems a little bit more user friendly but a bit more expensive. Any thoughts?

Hi Justin,

For some time, Elerion and I have been investigating suitable bench power supplies. I posted a report showing the findings and highlighted the best choice (in my opinion) in yellow: cost/size/weight/quality of design/quality of build/V range/I range etc trade-off. https://www.electro-tech-online.com/threads/product-specs.146657/page-3#post-1244608 post #46. It is a 0V to 30V, 0A to 10A model and costs around £40 UK including post and packing. I am on the verge of pulling the trigger and Elerion is still thinking. Yes, you do need that voltage and current range. Later you can get another of the same type PSU (to give +- supply lines) and that will be your PSU requirements taken care of. Time then to get into some serious electronics. They make good lead acid battery chargers too.

 

[spec]

I reached this thread tool late to contribute to the multimeter choosing - I would have said try to get a Brymen meter. Still loving the one I got in July

Yes, Brymen multimeters are brilliant. I thought at first that Justin's multimeter might have been OEM by Brymen but, as I said earlier, I'm now pretty sure it is made by/for Extech.

What model Brymen did you go for?

 

[KeepItSimpleStupid]

They make good lead acid battery chargers too.[/spec]

DO NOT DO THIS!! You MUST use a diode with a current rating greater than the charing current in series with the power supply.

It's nearly guaranteed to release Magic smoke: https://en.wikipedia.org/wiki/Magic_smoke

Don't ask me how I know.

 

[spec]

Only if you connect the power supply the wrong way around. You imply that it would happen under normal conditions.

 

[KeepItSimpleStupid]

It WILL happen under charging conditions. Check the big boys app notes.

 

[spec]

I have used lab PSUs stacks of times for charging 12V lead acid batteries. In fact I had one connected for a year or so with no problems at all. Why be cryptic: what are big boys app notes?

 

[KeepItSimpleStupid]

**broken link removed**

On phone. cant easily find better ones.

 

[spec]

That report is just a general chat- not specific. also remember that the PSU in question is a switching type, which tend to have reverse blocking by their very nature.
Had you have said it would be safest to put a diode in series I would have agreed but I can see no reason for all the drama in red.

 

[KeepItSimpleStupid]

Any supply with OVP, it's a big prolem. See **broken link removed**

Dunno if that supply has OVP.

PDF page 93.

What happens if OVP is activated, you get a direct short across the battery. Think crowbar protection.

 

[spec]

Any supply with OVP, it's a big prolem. See **broken link removed**

Dunno if that supply has OVP. PDF page 93. What happens if OVP is activated, you get a direct short across the battery. Think crowbar protection.

Depends on the Over Volt Protection (OVP) circuit design. But I see no evidence that the PSU in question has has a crowbar. I would be very surprised if it did. Besides which, I have used lab PSUs with crowbar protection and all the other protection you can imagine without problem. Like I said though, putting a diode in series with the battery is a wise precaution. The only thing, if you haven't got remote sense on the PSU you mess up the charging voltage cut off point which is 14.75V at 25 deg C, if I remember correctly. I cant remember which way a lead acid terminal voltage temp co goes either. Could be a diode would go the wrong way which would make matters worse.

 

[Justin Verrall]

Hi Justin,

For some time, Elerion and I have been investigating suitable bench power supplies. I posted a report showing the findings and highlighted the best choice (in my opinion) in yellow: cost/size/weight/quality of design/quality of build/V range/I range etc trade-off. https://www.electro-tech-online.com/threads/product-specs.146657/page-3#post-1244608 post #46. It is a 0V to 30V, 0A to 10A model and costs around £40 UK including post and packing. I am on the verge of pulling the trigger and Elerion is still thinking. Yes, you do need that voltage and current range. Later you can get another of the same type PSU (to give +- supply lines) and that will be your PSU requirements taken care of. Time then to get into some serious electronics. They make good lead acid battery chargers too.

I had a look at it and there are only 110-220V and NZ power runs on 230-240V as well as for the price I might as well get one of the ones in NZ but thank you for sharing that info with me I'll keep looking around in New Zealand web sights for possible cheaper options but other then that I might get the slightly cheaper option https://www.jaycar.co.nz/Power-Prod...t-Switchmode-Laboratory-Power-Supply/p/MP3800

 

[spec]

I had a look at it and there are only 110-220V and NZ power runs on 230-240V as well as for the price I might as well get one of the ones in NZ but thank you for sharing that info with me I'll keep looking around in New Zealand web sights for possible cheaper options but other then that I might get the slightly cheaper option https://www.jaycar.co.nz/Power-Prod...t-Switchmode-Laboratory-Power-Supply/p/MP3800

Hi Justin,

230 to 240V mains supply would be fine. If that was not the case the PSU would not be a viable product.

I don't like to be negative but I would not recommend the Jaycar PSU that you cited because:
(1) It has no current control. Unless I have missed it. That PSU could blast 15A into your test circuit under fault conditions which is very undesirable. The other thing is that you would not be able to use it for constant current applications, which you will need in the future.
(2) The terminals being on the back will be a nuisance.
(3) There is no earth terminal and no room to fit one

You say that the Jaycar PSU would be cheaper- how is that. The Ebay PSU would be $85 including post and packing but the Jaycar PSU is $179. Or have I got something wrong?

The other aspect is that the Ebay PSU is well designed and made- so might the Jaycar supply but I don't know. Also with mine I plan to do some mods like add another small 5V and possibly -15V supply. I think there is room, but there does not seem to be much room in the Jaycar supply.
Finally I think the Ebay supply has a more convenient form factor.

spec

 

[Justin Verrall]

Hi Justin,

230 to 240V mains supply would be fine. If that was not the case the PSU would not be a viable product.

I don't like to be negative but I would not recommend the Jaycar PSU that you cited because:
(1) It has no current control. Unless I have missed it. That PSU could blast 15A into your test circuit under fault conditions which is very undesirable. The other thing is that you would not be able to use it for constant current applications, which you will need in the future.
(2) The terminals being on the back will be a nuisance.
(3) There is no earth terminal and no room to fit one

You say that the Jaycar PSU would be cheaper- how is that. The Ebay PSU would be $85 including post and packing but the Jaycar PSU is $179. Or have I got something wrong?

The other aspect is that the Ebay PSU is well designed and made- so might the Jaycar supply but I don't know. Also with mine I plan to do some mods like add another small 5V and possibly -15V supply. I think there is room, but there does not seem to be much room in the Jaycar supply.
Finally I think the Ebay supply has a more convenient form factor.

spec

I think I jumped the gun in all honesty. I had a better look at it and your right so my next question is should I get the 3A 5A or 10A model?

 

[KeepItSimpleStupid]

This **broken link removed** basically says maybe for a blocking diode. I have one supply (linear) that I blew up 2x (723 reg) and I have a power mate (0-40 V, 0-3 A) that I blew up recently trying ti trickle charge an automotive battery. The PM has two 723's in it.

 

[spec]

I think I jumped the gun in all honesty. I had a better look at it and your right so my next question is should I get the 3A 5A or 10A model?

Get the 10A they are all the same size and similar design and same price. You will be glad to have 10A

 

[Justin Verrall]

Get the 10A they are all the same size and similar design and same price. You will be glad to have 10A

Will do!

 

[KeepItSimpleStupid]

This looks like more comprehensive specs for the same model: https://translate.google.com/transl...ace.com.tw/sell/show-3953891.html&prev=search

The stuff that you need to worry about is:
● ripple voltage: Vpp≤1% --> 50 mV p-p at 5V
● Digital display: three digit digit display.
● Display Resolution: 0.1V / 0.01A. ● Display accuracy: 100mV / 10mA ± 2digits.

This is a "regulated" power supply and "regulation" isn't even specified. 50 mV p-p is pretty respectable for a switching power supply.

I concur.

One thing that isn't obvious is that you can't seem to preset a current.

A digital supply I have has a Volts/amps selector, course fine adjusts, a power switch, and a front panel ground connection.

The binding posts are (+, earth and -), so difficult to use a dual banana. I have an analog supply that basically has the same things, but the arrangement of the banana's is a triagular pattern standard spaced.

This, https://www.ntecusa.com/test-equipm...tronix-ps280/8bd62b6a0def2ceb481d8aea71c1652f, has been highly recommended for a used supply.

 

[Justin Verrall]

This looks like more comprehensive specs for the same model: https://translate.google.com/transl...ace.com.tw/sell/show-3953891.html&prev=search

The stuff that you need to worry about is:
● ripple voltage: Vpp≤1% --> 50 mV p-p at 5V
● Digital display: three digit digit display.
● Display Resolution: 0.1V / 0.01A. ● Display accuracy: 100mV / 10mA ± 2digits.

This is a "regulated" power supply and "regulation" isn't even specified. 50 mV p-p is pretty respectable for a switching power supply.

I concur.

One thing that isn't obvious is that you can't seem to preset a current.

A digital supply I have has a Volts/amps selector, course fine adjusts, a power switch, and a front panel ground connection.

The binding posts are (+, earth and -), so difficult to use a dual banana. I have an analog supply that basically has the same things, but the arrangement of the banana's is a triagular pattern standard spaced.

This, https://www.ntecusa.com/test-equipm...tronix-ps280/8bd62b6a0def2ceb481d8aea71c1652f, has been highly recommended for a used supply.

Wait so this one would be better?