I just ordered the board from Pete. Looking forward to using it for my testing.
I do have some doubts as to the MDMV0000 part. It is expensive, very expensive!
Isn't there any way to replace it with another part? It just seems to be a simple voltmeter 5v powered. I have several (a dozen or so) assorted voltmeter panels which would serve the purpose of displaying voltage. If a 200mV display is required, I can either find one (should have one) or source it for less. Connections can be made with leads.
If a 200mV with 0.2% accuracy, 5v module is required then there are plenty of chinese backlit displays of similar size for as little as 6 euros shipped.
I do have some doubts as to the MDMV0000 part. It is expensive, very expensive!
Isn't there any way to replace it with another part? It just seems to be a simple voltmeter 5v powered. I have several (a dozen or so) assorted voltmeter panels which would serve the purpose of displaying voltage. If a 200mV display is required, I can either find one (should have one) or source it for less. Connections can be made with leads.
If a 200mV with 0.2% accuracy, 5v module is required then there are plenty of chinese backlit displays of similar size for as little as 6 euros shipped.
Last edited:
You don't need the meter if you have decent external meter, its very convenient, however. And, if you just want FFT's which are relative measurements then you can miss off the meter, the true RMS chip and the logic gates altogether, that will make it must cheaper to build.
I also seem to recall the free shipping break points and the needs for two orders, one from Digikey and one from Mouser, means two lots of shipping costs, this make the meter less expensive in reality than it really is.
The meter is a true RMS at all frequencies so you need to source one that's similar, a lot of cost effective DVM are only true RMS at 50Hz.
Andrew
I also seem to recall the free shipping break points and the needs for two orders, one from Digikey and one from Mouser, means two lots of shipping costs, this make the meter less expensive in reality than it really is.
The meter is a true RMS at all frequencies so you need to source one that's similar, a lot of cost effective DVM are only true RMS at 50Hz.
Andrew
Last edited:
the meter is expensive per se. I think the price is 60+ euros. For a Voltmeter that is expensive.
I thought the AD536 IC did the true rms work and simply sends a voltage signal to the panel meter for basic display purposes. The module itself by red lion does not seem to feature any true rms circuitry, but I may be wrong.
I thought the AD536 IC did the true rms work and simply sends a voltage signal to the panel meter for basic display purposes. The module itself by red lion does not seem to feature any true rms circuitry, but I may be wrong.
Yes the LCD is just that a display, I edited my posting after you posted, you could remove various bits if you don't want the meter; apologies if it wasn't clear.
But as I said I don't regret buying mine and I did contemplate not adding it. Also, you'll find that once you hook it up to a sound card that the various input and outputs values you need to drive the box to full scale mean you end up tweaking the sound card volumes lower than you expect, it only needs 500mV for full scale; having the meter gives you a point of reference otherwise its hard to know when your driving the ATEST box to clipping.
Also to get the noise floor down on mine I ended up shielding in the box, you need to blank the hole off in some way, I suspect.
Andrew
But as I said I don't regret buying mine and I did contemplate not adding it. Also, you'll find that once you hook it up to a sound card that the various input and outputs values you need to drive the box to full scale mean you end up tweaking the sound card volumes lower than you expect, it only needs 500mV for full scale; having the meter gives you a point of reference otherwise its hard to know when your driving the ATEST box to clipping.
Also to get the noise floor down on mine I ended up shielding in the box, you need to blank the hole off in some way, I suspect.
Andrew
Last edited:
Thanks for the reply. I now have confirmation that the display is just a display. If it is for reference during tweaking then I can find the least expensive compatible solution.
I hope no other component is that expensive or that hard to find.
Maybe an updated BOM could be useful for the forum if things have changed since the birth of the interface.
I hope no other component is that expensive or that hard to find.
Maybe an updated BOM could be useful for the forum if things have changed since the birth of the interface.
What I would do in your case if add a couple of 4mm banana plug sockets to the front panel and then plug in a DVM there so you can see what you are feeding into the system when you are setting things up.
The rest of the stuff is pretty standard I think we figured out some of the op amps could be upgraded but you'll be Ok with the ones Pete spec'd. I did have trouble finding the coupling caps but I wanted more uF to get the roll off out down lower.
Andrew
The rest of the stuff is pretty standard I think we figured out some of the op amps could be upgraded but you'll be Ok with the ones Pete spec'd. I did have trouble finding the coupling caps but I wanted more uF to get the roll off out down lower.
Andrew
Great! I'll just add IC sockets to allow for upgrades in the future.
The plug are actually a great idea, better yet those spring loaded connectors (as seen on amplifier backpanels). I like the idea of a standalone RMS meter so I may just complete the design and provide space for a battery pack and a switch.
The plug are actually a great idea, better yet those spring loaded connectors (as seen on amplifier backpanels). I like the idea of a standalone RMS meter so I may just complete the design and provide space for a battery pack and a switch.
different Voltmeter
Hey there, i used a different Voltmeter in my build, the EA-VK 1000 from a german distributor.
Its 26€, works well but needs a few changes to the ciruit. (i didnt use U2, R1,R3,R8,R10 and i connected the SW4A directly to the voltmeter, wiring it with short leads from the vm to the board since the connector doesnt fit)
EA VK1000 - 3-stelliges Mini-DVM bei reichelt elektronik
this might be another option for you,
cheers
Hey there, i used a different Voltmeter in my build, the EA-VK 1000 from a german distributor.
Its 26€, works well but needs a few changes to the ciruit. (i didnt use U2, R1,R3,R8,R10 and i connected the SW4A directly to the voltmeter, wiring it with short leads from the vm to the board since the connector doesnt fit)
EA VK1000 - 3-stelliges Mini-DVM bei reichelt elektronik
this might be another option for you,
cheers
Complete kit available
I've had many requests to source a complete parts kit for this. Especially outside the US, a few of the parts can be a little difficult to get. So, I went ahead and put together a few kits. They are on eBay:
Complete DIY Kit - Sound Card Interface / RMS Voltmeter | eBay
Pete
I've had many requests to source a complete parts kit for this. Especially outside the US, a few of the parts can be a little difficult to get. So, I went ahead and put together a few kits. They are on eBay:
Complete DIY Kit - Sound Card Interface / RMS Voltmeter | eBay
Pete
Sorry about that guys!
I avoided doing this for a long time because, frankly, it's a pain in the behind. Lots of parts to buy, put them all in little bags, etc. And obviously I need to charge more than it costs me
, so I was afraid the end cost would be too high and deter people from building it.
But I have it all set up now, so we'll see how it goes. I put together 5 kits and have had a lot of inquiries. If they disappear I'll kit up some more.
It does have me thinking... I wonder if there is demand for other kits. Like for power amps. I know there are a few out there, but most of them seem, well, not so great. Having grown up building Heathkits, I wonder if kitbuilding could be resurrected...
Maybe I should start a new thread on that?
Pete
I avoided doing this for a long time because, frankly, it's a pain in the behind. Lots of parts to buy, put them all in little bags, etc. And obviously I need to charge more than it costs me
, so I was afraid the end cost would be too high and deter people from building it.But I have it all set up now, so we'll see how it goes. I put together 5 kits and have had a lot of inquiries. If they disappear I'll kit up some more.
It does have me thinking... I wonder if there is demand for other kits. Like for power amps. I know there are a few out there, but most of them seem, well, not so great. Having grown up building Heathkits, I wonder if kitbuilding could be resurrected...
Maybe I should start a new thread on that?
Pete
Well, there IS a thread on here about the "resurrected" Heathkit, but I don't think there's been any activity for several months.
My unsubstantiated opinion is that yes, you probably COULD create a successful Heathkit-style business. The sales offerings will likely be a quickly-moving target based on discretionary and impulse purchases by gadget freaks and tinkerers, of rather fad-ish items. And a true Heathkit-style product isn't likely to be done by a couple of guys working out of a spare bedroom. Heathkits not only had some serious design (both electronic, and mechanical) behind them, but also some custom manufactured assemblies, extensive testing, and a LOT of effort to create the "Assembly Manual".
If "kit" means a box of parts, a schematic, and a silk-screened panel then probably the most successful vendors (Southwest Technical Products, Old Colony Labs, etc) have had affiliations with magazine publishers (Popular Electronics, Audio Amateur, Silicon Chip, etc).
Dale
I believe Pete is rather thinking of a "BOM to box" style kit. I think it would save a lot of time and trouble. I know for a fact that sourcing the material for Pete's projects can be around 70% more expensive in Europe than in the USA. Since Pete's projects are designed around specific parts (yes, they can be changed but it is something most inexperienced builders, like myself, don't do) it can happen than with taxes, fees, european prices, the BOM total is exceed by a fair amount. A single source of these parts, at US prices, plus whatever Pete feels is appropriate would be still be economically more convenient.
Also a great way for a beginner to get past the "sourcing" stage which is expensive and tedious and get right to the soldering.
Also a great way for a beginner to get past the "sourcing" stage which is expensive and tedious and get right to the soldering.
Sorry about that guys!
I avoided doing this for a long time because, frankly, it's a pain in the behind. Lots of parts to buy, put them all in little bags, etc. And obviously I need to charge more than it costs me
But I have it all set up now, so we'll see how it goes. I put together 5 kits and have had a lot of inquiries. If they disappear I'll kit up some more.
It does have me thinking... I wonder if there is demand for other kits. Like for power amps. I know there are a few out there, but most of them seem, well, not so great. Having grown up building Heathkits, I wonder if kitbuilding could be resurrected...
Maybe I should start a new thread on that?
Pete
I used to sell a kit amplifier based around the popular LM3886 called the Point Zero. It was a DC compensated design which set it apart from the competiton. I sold it with the heat sink and correct toroidal transformer which was difficult to source at that time so it was quite popular. It was extremely difficult to "kit up" enough parts to keep up with demands so I discontinued it after just 50 sets. It would require a small army to fulfill just one product...