Hi All,
I am a newbie to audio electronics and I was wondering if anybody could lend me a hand with the selection of Molex Connectors for an upcoming project.
I would like to build my first Audio amplifier and I would like to know if there are any standards in regards to what type of connector to use where.
I would like to build 7 different PCB boards and I am going to need to be able to connect them all together once its all mounted in a case or on the test bench.
I am thinking I would have
1. A PCB for the raw power supply
2. A PCB for the on switch & 240v A/C supply
3. A PCB for the Line level and XLR balanced inputs.
4. A PCB for the Input conditioning circuit prior to the Input stage (IPS).
5. A PCB for the Input stage (IPS), Voltage Amplification stage (VAS) and the output stage (OPS)
6. One PCB for each of the output protection circuits. These PCB's would also have mounting for the Output terminal posts.
7. A PCB mounting one led for each channel to show if a protection (Temperature / Output) is active.
Any input on this would be greatly appreciated.
I am a newbie to audio electronics and I was wondering if anybody could lend me a hand with the selection of Molex Connectors for an upcoming project.
I would like to build my first Audio amplifier and I would like to know if there are any standards in regards to what type of connector to use where.
I would like to build 7 different PCB boards and I am going to need to be able to connect them all together once its all mounted in a case or on the test bench.
I am thinking I would have
1. A PCB for the raw power supply
2. A PCB for the on switch & 240v A/C supply
3. A PCB for the Line level and XLR balanced inputs.
4. A PCB for the Input conditioning circuit prior to the Input stage (IPS).
5. A PCB for the Input stage (IPS), Voltage Amplification stage (VAS) and the output stage (OPS)
6. One PCB for each of the output protection circuits. These PCB's would also have mounting for the Output terminal posts.
7. A PCB mounting one led for each channel to show if a protection (Temperature / Output) is active.
Any input on this would be greatly appreciated.
I never use separate pcb's in my amps.
However with one pcb great care has to be taken in regards to the zero volt line.
Star grounding is vital. Allowing the likes of smoothing capacitor charging impulses to get into the audio ground can create massive hum.
One pcb gets rid of the connectors completely which gets rid of any possible bad connections on those connectors.
However with one pcb great care has to be taken in regards to the zero volt line.
Star grounding is vital. Allowing the likes of smoothing capacitor charging impulses to get into the audio ground can create massive hum.
One pcb gets rid of the connectors completely which gets rid of any possible bad connections on those connectors.
stuartmp, is this a project where you are putting into practice various circuit building blocks you have learned/designed? Is it a submission where individual parts are marked/assessed? (like a EE uni submission)
If not, and you are designing the amplifer, I can agree with Nigel that minimizing the individual PCB count is preferable where possible. If there are other reasons to have multiple PCBs (modular/ease of repair/cost etc), then at least combine the 240v section with switching (and use 240v rated connectors) and perhaps consider combining the XLR/input/VAS/output onto one PCB and the speaker protectors together on the output terminals.
Tell us more about the circuit and the intended reasoning behind the 7 pcbs.
If not, and you are designing the amplifer, I can agree with Nigel that minimizing the individual PCB count is preferable where possible. If there are other reasons to have multiple PCBs (modular/ease of repair/cost etc), then at least combine the 240v section with switching (and use 240v rated connectors) and perhaps consider combining the XLR/input/VAS/output onto one PCB and the speaker protectors together on the output terminals.
Tell us more about the circuit and the intended reasoning behind the 7 pcbs.
Thanks for that Input guy's.
I guess I was just trying to separate each section onto its own pcb this way in my mind at least I could revise or change individual sections of the amplifier without having the rebuild the whole thing and make another large PCB.
I have also opened up and worked on a few Yamaha integrated amplifiers and they seam to be quite modular. So I thought this practice was ok.
How ever I have also inspected a few Rotel Amplifiers and yes everything is basically on one board.
I guess my question still remains.
Is there are any standards in regards to connector on Amplifier boards?
Or what type of connectors do you suggest I use if I need to interconnect things as I'm not to keen on the idea of just soldering wires from one PCB to another as it makes it very difficult to dissemble or change things.
I guess I was just trying to separate each section onto its own pcb this way in my mind at least I could revise or change individual sections of the amplifier without having the rebuild the whole thing and make another large PCB.
I have also opened up and worked on a few Yamaha integrated amplifiers and they seam to be quite modular. So I thought this practice was ok.
How ever I have also inspected a few Rotel Amplifiers and yes everything is basically on one board.
I guess my question still remains.
Is there are any standards in regards to connector on Amplifier boards?
Or what type of connectors do you suggest I use if I need to interconnect things as I'm not to keen on the idea of just soldering wires from one PCB to another as it makes it very difficult to dissemble or change things.
They make a wide variety of connectors, and many can be used. Inline headers like the Molex KK-156 or the smaller KK-100 series can mount on a board, then use ribbon cables to connect the boards. There are "rectangular" connectors that come in all number of pins and a couple sizes, so you can use a wire harness and a square plastic body with pins in it. Look inside commercial products that have multiple boards, see the types of connectors they use.
My preference for low-power and signal connectors is the Molex KK-100 series (0.100" pitch) with gold plating. I generally use friction-latch pin headers on the PCB, e.g. 22-11-2042 if I want four pins. There are many types of mating connectors to choose from, but I tend to use IDC plugs from TE Connectivity often because they're so quick and easy to assemble. 640441-4 is an example 4-pin mating connector for 24 ga wire. You need a punch-down tool for this series, and you can't mix wire sizes. If you use them a LOT, then you might consider getting the industrial punch-down tool. It's expensive but most pleasant to use.
I use the Molex connectors 0.100" for the PCB's I've designed, but find that a lot of folks are not comfortable making up their own ribbon cables (as Mike states, the right tools make it much easier...) Digikey makes up ribbon cables with male, female and pigtail terminations in various lengths.
I use the JST XA for signal and low current stuff. Most recently JST VH fully shrouded variant for power but Molex's fit range for the most part has better specs for increased currents. You can order the JST stuff directly from their web-store and most varieties can be ordered in low quantity which is neat.
I like the XA, features a locking tab and properly weighted insertion. Buy them from JST and you get to colour code them too.
I use the Engineer PA-21 universal crimper for the contacts.
For all crimp contacts, stay within the recommended range of wire size, otherwise the crimp form will not work as intended.
I like the XA, features a locking tab and properly weighted insertion. Buy them from JST and you get to colour code them too.
I use the Engineer PA-21 universal crimper for the contacts.
For all crimp contacts, stay within the recommended range of wire size, otherwise the crimp form will not work as intended.
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