I'm considering hiring a freelance electrical engineer to produce circuit schematics for a remote control vehicle concept. My intent is to bring these schematics to a PCB designer to create Gerber files for manufacturing. How can I help my electrical engineer design a circuit schematic that best reflects the design intent of the vehicle?

So far I've compiled written and illustrated descriptions of the vehicle's function along with several rudimentary (and definitely flawed) attempts at circuit schematics. I also have conceptual mechanical drawings of the vehicle with approximated sizes and locations for electrical components. I have already selected motors, batteries, and external sensors, but would be open to suggestions from the person I hire.

What else can I bring to the table that will help facilitate effective collaboration between the mechanical and electrical halves of the project?

 

I'm usually on the software side of these types of things, but don't discount the benefit of getting people physically together in the same room to discuss and whiteboard. Also show the person as much of the physical project as you can, so they can put their hands on it and check it out. This helps them to see your vision. Get pizza and drinks and plan a full day. Also when you have something very complicated, try to break it into modules or parts. That can make problems easier to solve.

 

In addition to getting people together and getting them as aware of the context within which you are asking them to work, I would recommend focusing your efforts on defining the interfaces between what you are asking everyone to do. For instance, your PCB guy needs to know what the size and shape constraints are on a particular board, but your schematic guy doesn't (not directly). Your schematic guy needs to know what the circuit on that board needs to accomplish, but your board guy doesn't (not directly). So make sure they each know the details that are critical to what they are doing, but that they have a general awareness of what the other guy is doing. Then be sure that they are able to communicate with each other so that they can discover, early on, that the circuit is becoming too big for the board to accommodate or any one of a host of other things. Lateral communication between the parties most directly affected usually identifies and overcomes issues the quickest and cheapest. Don't add a layer of complexity by making them go through you.

Furthermore, I would downplay the prior attempts at circuit schematics. There is a reason that you are bringing onboard someone to design your circuits for you. Focus on making sure they know how the circuits need to behave and what constraints need to be met, then let them do their job designing circuits that behave that way and meet those constraints.

 

Furthermore, I would downplay the prior attempts at circuit schematics. There is a reason that you are bringing onboard someone to design your circuits for you. Focus on making sure they know how the circuits need to behave and what constraints need to be met, then let them do their job designing circuits that behave that way and meet those constraints.

WBahn gives good advice here. I recently had a marketing guy give me a specification for a new product that specified the use of a 10-bit A/D converter. After scolding him for giving me such rigid specs, I designed a circuit that gave me 3x the dynamic range and 4x the resolution that he required - with minimal additional engineering and cost - and allows the product to be more flexible in unknown field applications. A win for everyone.

You pay your engineers well. Let them engineer - but don't let them over engineer - it's a fine line. A good engineer knows the line.

I am always in constant communication with my mechanical engineering cohort. Board outlines and requirements can change quickly as the product is better understood and the ME will need to bounce ideas off of the EE and vice versa. You need to role with those punches and let them create to get the best quality product.

Also, generally speaking, you get better bang for your buck if your electrical design engineer also lays out the circuit boards. Most board layout guys I have worked with usually don't know the first thing about how the board layout can effect circuit performance - even in simple things like 4-wire current sense circuits. More times than not - I have sat with the board layout guy and said - "put this here", "put that here"... "no-no, The trace MUST be 2" long... not more, not less." They don't understand why - and I don't have time to teach them... they don't usually listen when I've tried to explain the details to them. That's been my experience anyway.

 

Bring the whole team in to "negotiate" the initial specifications for the design.
Top down "edicts" for design specifications are one of the best ways to waste time and lose creative opportunities.

Spend more time up front defining things as much as possible, this is where you discover the real problems that can bite you down the road.
Resist the temptation to "get started right away" with poorly defined tasks.

I could go on and on...

 

Thanks everybody, this is awesome advice. Would it be reasonable to ask for cost estimates from freelance designers if the scope of the project is well defined?

 

Thanks everybody, this is awesome advice. Would it be reasonable to ask for cost estimates from freelance designers if the scope of the project is well defined?

Sure. But be prepared for different policies from different folk -- so don't just look at the estimate, but be sure you understand the fine print. Some will give you an estimate but be very insistent that it is just an estimate and not a quote. Others will be leery of giving any estimate at all but, instead, insist on doing the job based on time and materials. Others will give you an estimate but still work for time an materials. Some will give you a firm fixed-price quote but reserve the right to abandon the project if it goes over budget unless an extension is agreed to. Others will give you a fixed price quote with some type of guarantee. In general, the more risk the freelancer assumes the higher the price will be.

 

I haven't done contract work for about 5 years - and I was charging just more than my normal engineering rate at my day job - but I needed the work and the money. I believe I was charging $40-50 an hour. A few years have passed so I have much more experience and I don't particularly need the work, but I always enjoy the extra income. I would probably charge somewhere between $95 - 120 an hour depending on the difficulty of the project, how bad I want to do the project, duration of the project, and if I could work from home or not. Any travel expenses would also be billable to the client. Although the rate is significantly more than I make at my day job - I also don't charge unproductive time when on contract - whereas working on salary will have periods of unproductive time. I'm crankin' when I'm contracting. Also, I would insist on doing just design and functional test work. production build ordering, manufacturing, subsequent redesigns, performance testing, etc can be done by someone else with a cheaper hourly rate.

 

make sure your team considers thermal effects and packaging requirements as part of the design. Too often I've seen these left to the back burner, and when problems come up, they cause a costly redesign.

 

I haven't done contract work for about 5 years - and I was charging just more than my normal engineering rate at my day job - but I needed the work and the money. I believe I was charging $40-50 an hour. A few years have passed so I have much more experience and I don't particularly need the work, but I always enjoy the extra income. I would probably charge somewhere between $95 - 120 an hour depending on ....

Charging about twice to as much as three times what your hourly rate as an employee would be is pretty typical since you are now responsible for all of the payroll taxes and benefits that your employer would normally cover. You get to pay an additional 7.65% right off the bat for payroll tax, you have to pay for your own health insurance, you have to pay for your own retirement plan, you have to pay for your own holidays and vacations, you have to pay for all of your office supplies, you have to provide all of your own equipment. Lot's of other things that go into running a business that your employer normally covers. The beauty of doing contracting on the side is that your day job still covers things like health insurance, which is a biggie.