RS-14 Multimeter review and peek inside - Page 1
Forum section: electronics / testgear

author: Deckert
author_rank: Regular Contributor
timestamp: May 28, 2016, 02:42:36 pm
content: Hi,A colleague bought this little multimeter for use around the house and lent it to me to do a video review of the unit. It's a really affordable meter, is fused on both 10A and mA scales, has a uA scale and is just generally a rather useful little meter. Yes, it's only 2000 counts, but very capable for it's size! The display is amazingly clear to read.At the time of writing, it sells for about Aus $31 or about 14 UK pounds, released as part of the "RS Pro" range of tools from RS Components. Also sold as the CEM-DT914 and HayesUK multimeter.RS stock code: 893-7896--deckert

author: joeqsmith
author_rank: Super Contributor
timestamp: May 28, 2016, 04:39:37 pm
content: Good job with the review. At 4:04, quick search on the 07D821K and it seems to be a MOV not a spark gap. Surprised they have the one trimmer exposed with the battery out. Maybe that is a common one that needs adjustment.

author: Mark Hennessy
author_rank: Frequent Contributor
timestamp: May 28, 2016, 05:14:19 pm
content: I've done a detailed review of the Bside ADM01 and ADM02 and RS-14. Why these? Because while waiting to for RS to get stocks of the RS-14, I spotted that the Bside meters are very similar, so picked them up - can never have too many multimeters, even disposable ones. All use the same IC, and all share problems as a result.http://golbornevintageradio.co.uk/forum/showthread.php?tid=5501The reviews were done "chronologically", so start with the ADM01, then cover the differences in the ADM02 when it arrived, and the same for the RS-14 when it finally landed. For that reason, it might make most sense to read the entire thread if you can bear it. But skip to post #6 for the RS model. In the fullness of time, I'll re-write the content in a more logical form and place it on my website.There are quite a few points raised that weren't mentioned in the video, such as the painfully slow response in ohms mode (the auto-ranging is fast, as shown in the video, but settling on a value within a range can take a few seconds), or the overshoot when reading volts. In many ways the RS-14 is better than those cheap Bside meters, but actually, it's not quite as clear-cut as that. For low voltage, low energy work, I'd take the Bside. The RS-14 is Cat III rated, but not independently verified as far as I've established so far, and although it's perhaps less likely to destroyitselfin a high-voltage transient event, I'm not sure if it offers better protection to theuserif it does blow up. The Bside is probably more robust because of the separate holster. The Bside might have a smaller display, but it has a *much* better viewing angle. The Bside doesn't slide around a hard worktop as you operate the range switch. But the Bside has horrid hard plastic buttons and "clicky" tact switches, and no manual ranging. But it's a lot cheaper.If you're wondering about the forum I put that in, it's worth saying that a lot of folk in the UK vintage radio community see nothing wrong with those horrible sub-£5 meters, so I was hoping to demonstrate that moving up the food chain just a small amount gets you so much more in terms of accuracy, functionality and safety. Obviously all these meters are a way off Fluke's standards, but a step in the right direction, hopefully.

author: Hydrawerk
author_rank: Super Contributor
timestamp: May 28, 2016, 07:15:34 pm
content: I do not like shared jacks for voltage and current.

author: Deckert
author_rank: Regular Contributor
timestamp: May 29, 2016, 02:19:54 pm
content: Quote from: joeqsmith on May 28, 2016, 04:39:37 pmAh, thanks for pointing that out, joeqsmith - I was going by the component silkscreen of SPG, but indeed the actual component is a MOV. I suppose both (MOV and SPG) could work in this configuration?--deckert

author: Deckert
author_rank: Regular Contributor
timestamp: May 29, 2016, 03:07:40 pm
content: Hi Mark,Quote from: Mark Hennessy on May 28, 2016, 05:14:19 pmExcellent review, nice hi-res pics.I didn't notice too long times while I tested the resistance accuracy, but one tends to sometimes miss some of that detail while filming. I went back to the raw footage, but I did not include the auto-ranging process in any clips. I'll ask my colleague if I can borrow the meter again for a day or so to include the ranging speeds in this thread.Also, agreed with your summary - it's no Fluke, but it's no Harbor Freight special, either. It fits in somewhere just above the cheapies, becoming useful and at least semi-safe.--deckert

author: joeqsmith
author_rank: Super Contributor
timestamp: May 29, 2016, 03:35:30 pm
content: When it comes to mistakes, I have no room to talk.A MOV and GDT are not interchangeable. They behave differently. Have a look at this video. Be sure and note the part number of the MOVs being tested!!Quote from: Deckert on May 29, 2016, 02:19:54 pm

author: mos6502
author_rank: Frequent Contributor
timestamp: May 29, 2016, 05:26:23 pm
content: Quote from: joeqsmith on May 29, 2016, 03:35:30 pmInteresting tests. Is there a reason why meter manufacturer don't use TVS diodes? In my experience, they work much better than MOVs.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 29, 2016, 06:06:56 pm
content: Quote from: mos6502 on May 29, 2016, 05:26:23 pmMy guess is low energy and cost. Would be interesting to sit in on some of the design reviews where they decide (we need MOVs) and then when they can't meet their cost targets when they decide to drop the MOVs!

author: mos6502
author_rank: Frequent Contributor
timestamp: May 29, 2016, 06:31:43 pm
content: There's ways to increase the power rating:http://www.vishay.com/docs/88451/stacking.pdfA few years back I built a TV flyback driver. Basically a TL494 for adjustable frequency and duty cycle and a FET. FET kept blowing. Put a 12V MOV on the gate. FET kept blowing. Removed the MOV, put a 12V TVS on the gate. Worked fine ever after.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 29, 2016, 07:52:28 pm
content: Fairly old app note. They make higher voltage parts now. But in the end they do talk about the cost. They are fast though. That PLC I showed uses TVS / PTC protection.