Greetings from Balmy, snowy Michigan!!
Seeking guidance producing PCBs for a couple of amateur radio audio projects. They are quite simple and not terribly exciting. I focus more on utility than complexity.
BACKGROUND:
Most amateur radio transceivers are designed to use hand held dynamic microphones which have relatively low output signal levels compared to most computer gaming headsets with electret condenser capsules. Many operators prefer close-talked dynamic microphones because they are generally better at “rejecting” ambient noise, such as loud cooling fans, barking dogs, marauding grandchildren, and a wife shouting orders from a three year old “TO DO” list. Other operators prefer computer widely available computer gaming headsets because they are lightweight, provide some isolation from ambient noise, provide good “communications grade” audio, and especially because they are available at comparatively low cost. (Ham operators are notoriously frugal, i.e., really CHEAP! Nearly all modern transceiver provide 10v bias voltage to power small electret capsules.
The rub is, electret capsules are often often too loud and overdrive the rig/s audio input stage, motivating operators to seek some way to attenuate the signal to provide sufficient headroom to avoid distortion.
SOLUTION:
My little circuit does two things: 1) A two-resistor L-pad attenuates high signal levels produced by electret capsules to approximate lower levels from dynamic cartridges. 2) A resistor reduces bias voltage by very roughly half (more or less) which protects the capsule from high voltage and (to my ears) produces a slightly less shrill, more natural sound (based on empirical observation, broad notions of how electret capsules work, and no scientific foundation or evidence whatsoever. Just trust me, ****ie . . .)
My schematic diagram has three variations for routing bias voltage. I once made an image depicting board traces with an on-line, browser-based program provided by PCB maker, www. FarCircuits.com. (See attached images)
The circuit works as intended, has been vetted by numerous operators, and was published in the November 2013 issue of QST Magazine, which has the widest circulation of any amateur radio publication. (Publish or perish, ya know, which also proves I am a real person after all.)
OBJECTIVE:
Produce small, low cost, easy to populate PCB’s so other ops can make and use this circuit to better match their computer style gaming headsets to their transceivers. I want to make them as small as practicable and fit in a very small plastic or metal project box, yet easy for older hands to make. Optimally, it should be small enough to install inline as part of a headset’s cable to the rig. Yep, I want my cake and, also, serve it to friends.
QUESTIONS:
1) What are the currently preferred sources for purchasing low cost PCBs?
2) How can I convert the Version 3 schematic to a format used by PCB manufacturers? Is there a standard format or most popular program to accomplish this?
3) What (approximately) should I expect to pay for finished boards? I believe most vendors charge a minimum fee for a minimum number of boards with as many circuits as I can fir on them. Is this correct?
4) Can the parts layout be optimized, simplified, or improved to reduce the size of finished boards?
5) Is it cost-effective to have the PCB maker populate the boards as finished goods? OR should I simply provide boards, OR, perhaps, provide boards with loose parts as a kit? I will charge a nominal fee to cover the cost of postage and goods sold. I do not seek to make a profit, nor to run a charity.
6) Is anyone willing and able to convert my project into files which can be used to order boards from a preferred vendor?
Perhaps some boy genius with surplus time on his hands could pencil whip this into a ready-to-order state. I am not lazy, just an opportunist hoping to chart the most expeditious course, of course. Considering other operators will rely on my work, I want to get it right the first time.
6) What else should I ask ? Am I missing anything?
Any assistance will be greatly appreciated as I attempt to produce a quantity of small circuit boards for others to use.
Happy trails to all. James
Seeking guidance producing PCBs for a couple of amateur radio audio projects. They are quite simple and not terribly exciting. I focus more on utility than complexity.
BACKGROUND:
Most amateur radio transceivers are designed to use hand held dynamic microphones which have relatively low output signal levels compared to most computer gaming headsets with electret condenser capsules. Many operators prefer close-talked dynamic microphones because they are generally better at “rejecting” ambient noise, such as loud cooling fans, barking dogs, marauding grandchildren, and a wife shouting orders from a three year old “TO DO” list. Other operators prefer computer widely available computer gaming headsets because they are lightweight, provide some isolation from ambient noise, provide good “communications grade” audio, and especially because they are available at comparatively low cost. (Ham operators are notoriously frugal, i.e., really CHEAP! Nearly all modern transceiver provide 10v bias voltage to power small electret capsules.
The rub is, electret capsules are often often too loud and overdrive the rig/s audio input stage, motivating operators to seek some way to attenuate the signal to provide sufficient headroom to avoid distortion.
SOLUTION:
My little circuit does two things: 1) A two-resistor L-pad attenuates high signal levels produced by electret capsules to approximate lower levels from dynamic cartridges. 2) A resistor reduces bias voltage by very roughly half (more or less) which protects the capsule from high voltage and (to my ears) produces a slightly less shrill, more natural sound (based on empirical observation, broad notions of how electret capsules work, and no scientific foundation or evidence whatsoever. Just trust me, ****ie . . .)
My schematic diagram has three variations for routing bias voltage. I once made an image depicting board traces with an on-line, browser-based program provided by PCB maker, www. FarCircuits.com. (See attached images)
The circuit works as intended, has been vetted by numerous operators, and was published in the November 2013 issue of QST Magazine, which has the widest circulation of any amateur radio publication. (Publish or perish, ya know, which also proves I am a real person after all.)
OBJECTIVE:
Produce small, low cost, easy to populate PCB’s so other ops can make and use this circuit to better match their computer style gaming headsets to their transceivers. I want to make them as small as practicable and fit in a very small plastic or metal project box, yet easy for older hands to make. Optimally, it should be small enough to install inline as part of a headset’s cable to the rig. Yep, I want my cake and, also, serve it to friends.
QUESTIONS:
1) What are the currently preferred sources for purchasing low cost PCBs?
2) How can I convert the Version 3 schematic to a format used by PCB manufacturers? Is there a standard format or most popular program to accomplish this?
3) What (approximately) should I expect to pay for finished boards? I believe most vendors charge a minimum fee for a minimum number of boards with as many circuits as I can fir on them. Is this correct?
4) Can the parts layout be optimized, simplified, or improved to reduce the size of finished boards?
5) Is it cost-effective to have the PCB maker populate the boards as finished goods? OR should I simply provide boards, OR, perhaps, provide boards with loose parts as a kit? I will charge a nominal fee to cover the cost of postage and goods sold. I do not seek to make a profit, nor to run a charity.
6) Is anyone willing and able to convert my project into files which can be used to order boards from a preferred vendor?
Perhaps some boy genius with surplus time on his hands could pencil whip this into a ready-to-order state. I am not lazy, just an opportunist hoping to chart the most expeditious course, of course. Considering other operators will rely on my work, I want to get it right the first time.
6) What else should I ask ? Am I missing anything?
Any assistance will be greatly appreciated as I attempt to produce a quantity of small circuit boards for others to use.
Happy trails to all. James
