EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: hmjgriffon on July 12, 2020, 03:57:58 pm
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I searched the entire forum and found a few posts of people asking about bench supplies but not much information found and people with low budgets. I am looking for a bench supply, my first, but I want to get a fairly good one. Budget is variable, I've been reading, watching youtube videos etc. I was looking at some supplies like the Siglent Technologies SPD3303C or something from Rigol, I watched some teardown videos and things such as EEVblog of the SPD3303C and it didn't go very well, didn't know if the issues in that video have been solved as it was pretty old. Also I read the rigols come with extra features that you have to unlock with serial numbers. I also read some reviews on amazon for one of their oscilloscope's that people bought it and everything came unlocked. I know there is a website out there that can generate codes to unlock, but not sure if it works on all of the current models and firmwares? Something bugs me about buying a thing with features arbitrarily locked to get more money out of you.
So essentially it looks like I'm looking at things in the $300-$500 range, I was thinking 30V 5A would be great and multiple outputs. But I am mostly doing things with micro controllers, sensors, other things in home automation and stuff like that so maybe I could get away with 15V 3A or something if it means getting a better unit for the same money. I'd like something that doesn't have issues, has clean output, won't kill components when I turn the output power on, something a guy like Dave from eevblog would actually recommend haha. I'm kind of a buy once cry once kind of person but I'm also a beginner so I don't need some super high end supply an electrical engineer would use, I don't want something that is trash though either, I wanna be able to grow into it, not grow out of it.
If there is already a thread about bench supplies that is kept up to date let me know, I saw one for multi-meters and such, I'm surprised I couldn't find one for bench supplies. I came to eevblog because everywhere else I ask for advice it seems everyone is perfectly happy to use a cheap $70 bench supply, I need advice from smart people who aren't afraid to buy good equipment. As an example my first and second multi meter were a fluke 101, and then a brymen 869s.
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Hi,
I´m perfectly confident with my SPD3303C. I rather like the knob interface and prefer it over buttons.
The 7-Segment display may appear old fashioned, but it shows what you want and need to know in sufficiently large sized characters without the distractive info-overflow of many modern TFT-displays.
Its sufficiently precise, low noise and switches with clean transients. In this it seems to be exactly the same as its pricier brother SPD3303X-E.
It can be remotely programmed via the associated software if required.
I´d buy it again.
regards
Calvin
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The reason there are so many different models is that there are so many different use cases. I have several, the one that sits on my bench is a BK Precision 1652 (the newer, digital version) which might seen a silly choice given its price new, but it is linear, doesn't spike the output on turn on, is robustly protected, can be used as a battery charger and has 1mA resolution on the current adjustment. That last one is handy when I'm converting old audio equipment to LED lighting--I can install the LEDs and adjust the current until I like the brightness, then select the right dropping resistor the first time. And they turn up on eBay in good condition for $100-150 or so. OTOH, it is a huge clunker, only 0.5A/channel on the two main outputs and 5V only on the third.
So, do you need or want things like precise current control, precise voltage control, low noise, protection against backfeeding/shorts/reverse polarity, programmability, battery charging and so on?
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I'll second everything Calvin said. I've had the SPD3303C for a little over 2 years and though it gets used lightly, I've been very happy with it and haven't had any problems (knock on wood).
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All SPD****X model displays are just so nice. Fans quiet with low loads and outputs are well behaved at power ON and channel ON.
Super clean outputs and sense terminals on the SDP1000X models.
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I don't have any of the "modern" supplies at the moment. However there are a few important points you should consider before settling on any supply.
- In the long run you will likely need more than one.
- If your focus is on microprocessors and interfacing "stuff" to them, you really will want a multi output unit. That means a lower voltage supply for the microprocessor. The power supply for the I/O stuff should be a wider range supply. It might be advisable to have two wider range supplies for things like OP Amps that might require negative and positive rails.
- Since you will need more than one at some point building your own is a good learning experience. Such a supply does not need to be excessively fancy.
- Fixed voltage supplies are often a good alternative to variable. For instance at work we have a lot of 24 VDC systems and having a 24 VDC supply ready to go is extremely handy. Do make sure that the supply is short circuit protected. Some people may dismiss fixed voltage supplies but if you use a specific voltage range a lot they can actually prevent trouble by not being adjustable. This applies to your microprocessor supply too, a fixed output will not let you burn out the circuit be accidentally turning the wrong knob or pushing the wrong button.
- Never dismiss used hardware. Often this can mean higher quality at bargain basement prices.
- The digital panel meters on modern supplies that constantly display current and voltage are very nice and can help reduce the need for many multimeters
- Seriously consider one very good supply and "if and when" needed lower end units. This is sort of like having one very good multimeter for reliable measurements and cheapy meters for lesser bench usage.
- Unless you have a specific need I'd consider multi outputs over excessive current capacity. For example your 0-30 VDC outputs should ideally be between 0.5 and 1 amp. Your low voltage supply, 0-5 VDC, for example probably should be between 3 and 5 amps. The idea here is to get started in microprocesors with plenty of power for the digital end and enough flexibility for what every you might need in the other supplies without breaking the bank.
So in the end I really don't buy the idea that there is one power supply to serve all needs. The trick is to buy one that can get your started and does so without killing the budding desire you have with respect to electronics. Frankly you don't need a lot to get started, I can remember using some batteries and a regulator. You can literally run microprocessor projects off a wall wart is needed. By the way not dismissing all the good features a modern supply has just that they are not a requirement to get started.
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My first 10 years in the hobby all I had was a home made supply built following a schematic in a Forrest Mims book using parts from Radio Shack. Even today, I can't bring myself to spend hundreds of dollars for a power supply. Used stuff from eBay has done a good job so far.
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I managed to find a GW Instek GPD-3303S used on eBay for about 1/2 what the Siglent SPD3303C power supply cost new. The resolution and accuracy was about 10 time better than the Siglent so I'm happy with that GW Instek supply. Actually I bought a second one at an equally good price that was a newer supply with the same model number but had a newer revised circuit board. This newer revision had an overshoot problem on the lower voltage fixed supply but someone had found a fix that corrected the problem and it worked to correct this problem.
I like having the ability to calibrate these supplies without removing the covers or tweaking multiple pots. Some of the other supplies I looked at would have worked but with the features and the good price on these used I couldn't pass them up.
I also bought a used single output GW Instek PSM-2010 supply that will output more current and has remote sensing that I'm equally pleased with.
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I managed to find a GW Instek GPD-3303S used on eBay for about 1/2 what the Siglent SPD3303C power supply cost new. The resolution and accuracy was about 10 time better than the Siglent so I'm happy with that GW Instek supply. Actually I bought a second one at an equally good price that was a newer supply with the same model number but had a newer revised circuit board. This newer revision had an overshoot problem on the lower voltage fixed supply but someone had found a fix that corrected the problem and it worked to correct this problem.
Was that a power-on overshoot? Do you know of the GPD-3303S can be used as a battery charger? IOW, is it protected against reverse (sink) current flow if connected to a battery while the power is off? This is different from reverse polarity protection and I can't find any mention of this in the manual or advertising.
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I managed to find a GW Instek GPD-3303S used on eBay for about 1/2 what the Siglent SPD3303C power supply cost new. The resolution and accuracy was about 10 time better than the Siglent so I'm happy with that GW Instek supply. Actually I bought a second one at an equally good price that was a newer supply with the same model number but had a newer revised circuit board. This newer revision had an overshoot problem on the lower voltage fixed supply but someone had found a fix that corrected the problem and it worked to correct this problem.
Was that a power-on overshoot? Do you know of the GPD-3303S can be used as a battery charger? IOW, is it protected against reverse (sink) current flow if connected to a battery while the power is off? This is different from reverse polarity protection and I can't find any mention of this in the manual or advertising.
Any PSU with an output relay offers reverse current protection when power is OFF.
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My first 10 years in the hobby all I had was a home made supply built following a schematic in a Forrest Mims book using parts from Radio Shack. Even today, I can't bring myself to spend hundreds of dollars for a power supply. Used stuff from eBay has done a good job so far.
I honestly believe that these fancy bench supplies are about the worse place somebody new to the hobby can throw his money! It would be far better to outfit the bench with a good scope and a bench multimeter and probably a few other instruments first.
On the flip side I have nothing against a good power supply on the bench. It is just the case that a person new to the hobby has options that don't break the bank. Like you I got by with very little back in the day. Three terminal regulators and a few TTL circuits are about all I had. Back then having something like a scope or a bench DMM (or even a hand held for that matter) was unheard of. Well not in my economic bracket at the time.
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Any PSU with an output relay offers reverse current protection when power is OFF.
Perhaps true--but that doesn't actually answer the question, does it? Also, I guess I should ask if it is protected against backfeed if the power is on but the set voltage is below the battery voltage.
And while you're at it, why doesn't the Siglent model offer more precision--1mA/1mV steps are what I would want. I like the display that shows the set and actual values at the same time, but the lack of resolution is a deal killer.
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Any PSU with an output relay offers reverse current protection when power is OFF.
Perhaps true--but that doesn't actually answer the question, does it? Also, I guess I should ask if it is protected against backfeed if the power is on but the set voltage is below the battery voltage.
Yeah well when the channel is ON and you supply reverse current/voltage above what the output is set to all bets are off. :scared:
And while you're at it, why doesn't the Siglent model offer more precision--1mA/1mV steps are what I would want. I like the display that shows the set and actual values at the same time, but the lack of resolution is a deal killer.
Only in the SDP3303X-E however when using the EasyPower SW the SPD3303X-E works at 1mA/mV instead of 10mA/mV.
All SPD ****X models offer 1mA/mV set points and resolution.
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I bought the SPD3303C some time ago, and although I'm happy with it, I still regret that I didn't pay a little more for the SPD3303X-E.
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Yeah well when the channel is ON and you supply reverse current/voltage above what the output is set to all bets are off. :scared:
No reason for this to blow anything up and it isn't an unreasonable requirement. It should either not react at all (diode in the output preventing reverse current flow) or sink the current up to the maximum rating and then trip off the output relay as protection. Otherwise it can't be qualified for battery charging because this is exactly what happens if you reduce the voltage a bit too far during battery charging.
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I too picked up a used GW Instek GPD-3303S off eBay for under $200 shipped and am very happy with it.
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I just bought a BK Precision 1671A here for $199 with free shipping:
https://www.valuetronics.com/product/1671a-bk-precision-dc-power-supply-new (https://www.valuetronics.com/product/1671a-bk-precision-dc-power-supply-new)
It's a fantastic power supply at a great price.